Six female Greenpeace protesters are scaling The Shard in a bid to highlight oil drilling in the Arctic.
The experienced climbers set out to ascend the 310m London landmark near London Bridge station, and as soon as it hit rush hour, the crowds started to gather.
Commuters stood and gawped at the bottom of Europe's tallest building, painfully arching their necks - making them look like extras from a zombie movie.
Earlier, a spokesman from the Metropolitan police told The Huffington Post UK officers had been called to the scene at 4.20am, when the climbers are believed to have started their ascent.
Officers were joined by those from the British Transport Police, but so far there have been no arrests.
The environmental protesters, who are described as activists and artists, are thought to have climbed to the top of London Bridge station to access the 72-storey skyscraper.
Zombies gather in a scene from 'Shaun of the Dead'
Greenpeace said it had chosen The Shard because it towered over the London offices of Shell, which it said was leading controversial drilling in the Arctic.
Once they reach the top of The Shard the group plan to unveil a large piece of artwork.
Londoners Turn Into Zombies
Greenpeace Protesters Climb Up The Shard(01 of14)
LONDON, UNITED KINGDOM - JULY 11: Onlookers watch as members of Greenpeace scale the Shard, the tallest building in western Europe, on July 11, 2013, in London, England. The six female protesters began their unauthorised ascent of the 310 metre high skyscraper shortly after 4am with the intention of highlighting the environmental damage caused by drilling for oil in the Arctic by Shell. (Photo by Warrick Page/Getty Images) (credit:Getty Images)
Greenpeace Protesters Climb Up The Shard(02 of14)
LONDON, UNITED KINGDOM - JULY 11: Onlookers watch as members of Greenpeace scale the Shard, the tallest building in western Europe, on July 11, 2013, in London, England. The six female protesters began their unauthorised ascent of the 310 metre high skyscraper shortly after 4am with the intention of highlighting the environmental damage caused by drilling for oil in the Arctic by Shell. (Photo by Warrick Page/Getty Images) (credit:Getty Images)
Greenpeace Protesters Climb Up The Shard(03 of14)
LONDON, UNITED KINGDOM - JULY 11: Onlookers watch as members of Greenpeace scale the Shard, the tallest building in western Europe, on July 11, 2013, in London, England. The six female protesters began their unauthorised ascent of the 310 metre high skyscraper shortly after 4am with the intention of highlighting the environmental damage caused by drilling for oil in the Arctic by Shell. (Photo by Warrick Page/Getty Images) (credit:Getty Images)
Greenpeace protest at the Shard(04 of14)
Onlooker watch a group of six women Greenpeace activists as they climb the Shard in central London, in protest at drilling in the Arctic. (credit:PA)
Greenpeace protest at the Shard(05 of14)
Onlooker watch a group of six women Greenpeace activists as they climb the Shard in central London, in protest at drilling in the Arctic. (credit:PA)
Greenpeace protest at the Shard(06 of14)
Onlooker watch a group of six women Greenpeace activists as they climb the Shard in central London, in protest at drilling in the Arctic. (credit:PA)
Onlooker watch a group of six women Greenpeace activists as they climb the Shard in central London, in protest at drilling in the Arctic.(07 of14)
Onlooker watch a group of six women Greenpeace activists as they climb the Shard in central London, in protest at drilling in the Arctic.
Greenpeace Protesters Climb Up The Shard(08 of14)
LONDON, ENGLAND - JULY 11: Protesters from the environmental charity Greenpeace attempt to scale the tallest building in western Europe, The Shard, in a bid to unveil a giant banner from the top on July 11, 2013 in London, England. The six female protesters began their unauthorised ascent of the 310 metre high skyscraper shortly after 4am with the intention of highlighting the environmental damage caused by drilling for oil in the Arctic by Shell. (Photo by Oli Scarff/Getty Images) (credit:Getty Images)
Greenpeace Protesters Climb Up The Shard(09 of14)
LONDON, ENGLAND - JULY 11: A protester from the environmental charity Greenpeace is watched by workers as she attempts to scale the tallest building in western Europe, The Shard, in a bid to unveil a giant banner from the top on July 11, 2013 in London, England. The six female protesters began their unauthorised ascent of the 310 metre high skyscraper shortly after 4am with the intention of highlighting the environmental damage caused by drilling for oil in the Arctic by Shell. (Photo by Oli Scarff/Getty Images) (credit:Getty Images)
Greenpeace Protesters Climb Up The Shard(10 of14)
LONDON, ENGLAND - JULY 11: Protesters from the environmental charity Greenpeace attempt to scale the tallest building in western Europe, The Shard, in a bid to unveil a giant banner from the top on July 11, 2013 in London, England. The six female protesters began their unauthorised ascent of the 310 metre high skyscraper shortly after 4am with the intention of highlighting the environmental damage caused by drilling for oil in the Arctic by Shell. (Photo by Oli Scarff/Getty Images) (credit:Getty Images)
Greenpeace Protesters Climb Up The Shard(11 of14)
LONDON, ENGLAND - JULY 11: Protesters from the environmental charity Greenpeace attempt to scale the tallest building in western Europe, The Shard, in a bid to unveil a giant banner from the top on July 11, 2013 in London, England. The six female protesters began their unauthorised ascent of the 310 metre high skyscraper shortly after 4am with the intention of highlighting the environmental damage caused by drilling for oil in the Arctic by Shell. (Photo by Oli Scarff/Getty Images) (credit:Getty Images)
Greenpeace Protesters Climb Up The Shard(12 of14)
LONDON, ENGLAND - JULY 11: A protester from the environmental charity Greenpeace attempts to scale the tallest building in western Europe, The Shard, in a bid to unveil a giant banner from the top on July 11, 2013 in London, England. The six female protesters began their unauthorised ascent of the 310 metre high skyscraper shortly after 4am with the intention of highlighting the environmental damage caused by drilling for oil in the Arctic by Shell. (Photo by Oli Scarff/Getty Images) (credit:Getty Images)
Skyscrapers Take Over The City Of London's Skyline(13 of14)
LONDON, ENGLAND - JULY 10: Window cleaners work on the 72-storey Shard skyscraper, which stands as the tallest building in Western Europe, on July 10, 2013 in London, England. Numerous skyscrapers are currently under construction in the capital which are set to redefine the composition of the London skyline in the coming years. Regulations in the 'London View Management Framework' restrict construction to protect certain key views across the capital from parks and public spaces that take in important buildings or urban landscapes which define London. (Photo by Oli Scarff/Getty Images) (credit:Getty Images)
Greenpeace Protesters Climb Up The Shard(14 of14)
LONDON, ENGLAND - JULY 11: A protester from the environmental charity Greenpeace is watched by workers as she attempts to scale the tallest building in western Europe, The Shard, in a bid to unveil a giant banner from the top on July 11, 2013 in London, England. The six female protesters began their unauthorised ascent of the 310 metre high skyscraper shortly after 4am with the intention of highlighting the environmental damage caused by drilling for oil in the Arctic by Shell. (Photo by Oli Scarff/Getty Images) (credit:Getty Images)
Greenpeace Activists Climb The Shard
Greenpeace Protesters Climb Up The Shard(01 of42)
LONDON, ENGLAND - JULY 11: A protester from the environmental charity Greenpeace is watched by workers as she attempts to scale the tallest building in western Europe, The Shard, in a bid to unveil a giant banner from the top on July 11, 2013 in London, England. The six female protesters began their unauthorised ascent of the 310 metre high skyscraper shortly after 4am with the intention of highlighting the environmental damage caused by drilling for oil in the Arctic by Shell. (Photo by Oli Scarff/Getty Images) (credit:Getty Images)
Greenpeace Protesters Climb Up The Shard(02 of42)
LONDON, ENGLAND - JULY 11: Protesters from the environmental charity Greenpeace attempt to scale the tallest building in western Europe, The Shard, in a bid to unveil a giant banner from the top on July 11, 2013 in London, England. The six female protesters began their unauthorised ascent of the 310 metre high skyscraper shortly after 4am with the intention of highlighting the environmental damage caused by drilling for oil in the Arctic by Shell. (Photo by Oli Scarff/Getty Images) (credit:Getty Images)
Greenpeace Protesters Climb Up The Shard(03 of42)
LONDON, ENGLAND - JULY 11: Protesters from the environmental charity Greenpeace are watched by workers as they attempt to scale the tallest building in western Europe, The Shard, in a bid to unveil a giant banner from the top on July 11, 2013 in London, England. The six female protesters began their unauthorised ascent of the 310 metre high skyscraper shortly after 4am with the intention of highlighting the environmental damage caused by drilling for oil in the Arctic by Shell. (Photo by Oli Scarff/Getty Images) (credit:Getty Images)
Greenpeace Protesters Climb Up The Shard(04 of42)
LONDON, ENGLAND - JULY 11: A protester from the environmental charity Greenpeace is watched by workers as she attempts to scale the tallest building in western Europe, The Shard, in a bid to unveil a giant banner from the top on July 11, 2013 in London, England. The six female protesters began their unauthorised ascent of the 310 metre high skyscraper shortly after 4am with the intention of highlighting the environmental damage caused by drilling for oil in the Arctic by Shell. (Photo by Oli Scarff/Getty Images) (credit:Getty Images)
Greenpeace Protesters Climb Up The Shard(05 of42)
LONDON, ENGLAND - JULY 11: A protester from the environmental charity Greenpeace is watched by workers as she attempts to scale the tallest building in western Europe, The Shard, in a bid to unveil a giant banner from the top on July 11, 2013 in London, England. The six female protesters began their unauthorised ascent of the 310 metre high skyscraper shortly after 4am with the intention of highlighting the environmental damage caused by drilling for oil in the Arctic by Shell. (Photo by Oli Scarff/Getty Images) (credit:Getty Images)
Greenpeace Protesters Climb Up The Shard(06 of42)
LONDON, ENGLAND - JULY 11: Protesters from the environmental charity Greenpeace attempt to scale the tallest building in western Europe, The Shard, in a bid to unveil a giant banner from the top on July 11, 2013 in London, England. The six female protesters began their unauthorised ascent of the 310 metre high skyscraper shortly after 4am with the intention of highlighting the environmental damage caused by drilling for oil in the Arctic by Shell. (Photo by Oli Scarff/Getty Images) (credit:Getty Images)
Greenpeace Protesters Climb Up The Shard(07 of42)
LONDON, ENGLAND - JULY 11: Protesters from the environmental charity Greenpeace attempt to scale the tallest building in western Europe, The Shard, in a bid to unveil a giant banner from the top on July 11, 2013 in London, England. The six female protesters began their unauthorised ascent of the 310 metre high skyscraper shortly after 4am with the intention of highlighting the environmental damage caused by drilling for oil in the Arctic by Shell. (Photo by Oli Scarff/Getty Images) (credit:Getty Images)
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People watch Greenpeace protesters climb up The Shard, the tallest building in western Europe, during a protest against the oil company Shell's drilling in the Arctic, Thursday, July 11, 2013. (AP Photo/Sang Tan) (credit:AP)
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Reflected in a nearby building, Greenpeace protesters climb up The Shard, the tallest building in western Europe, during a protest against the oil company Shell's drilling in the Arctic, Thursday, July 11, 2013. (AP Photo/Sang Tan) (credit:AP)
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Reflected in a nearby building, Greenpeace protesters climb up The Shard, the tallest building in western Europe, during a protest against the oil company Shell's drilling in the Arctic, Thursday, July 11, 2013. (AP Photo/Sang Tan) (credit:AP)
Greenpeace protest at the Shard(11 of42)
Greenpeace activists, part of a group of six women, as they climb the Shard in central London, in protest at drilling in the Arctic. (credit:PA)
Greenpeace protest at the Shard(12 of42)
A Greenpeace activist, part of a group of six women, as they climb the Shard in central London, in protest at drilling in the Arctic. (credit:PA)
Greenpeace protest at the Shard(13 of42)
Onlooker watch a group of six women Greenpeace activists as they climb the Shard in central London, in protest at drilling in the Arctic. (credit:PA)
Greenpeace protest at the Shard(14 of42)
Onlooker watch a group of six women Greenpeace activists as they climb the Shard in central London, in protest at drilling in the Arctic. (credit:PA)
Greenpeace protest at the Shard(15 of42)
Greenpeace activists, part of a group of six women, as they climb the Shard in central London, in protest at drilling in the Arctic. (credit:PA)
Greenpeace protest at the Shard(16 of42)
Greenpeace activists, part of a group of six women, as they climb the Shard in central London, in protest at drilling in the Arctic. (credit:PA)
six Greenpeace protesters climbs up The Shard,(17 of42)
Ali (blue helmet) hangs on while Sandra (black helmet) does... what is she doing? #iceclimb
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One of six Greenpeace protesters climbs up The Shard, the tallest building in western Europe, as workers look from a window, during a protest against the oil company Shell's drilling in the Arctic, Thursday, July 11, 2013. (AP Photo/Sang Tan) (credit:AP)
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Greenpeace protesters climbs up The Shard, the tallest building in western Europe, during a protest against the oil company Shell's drilling in the Arctic, Thursday, July 11, 2013. (AP Photo/Sang Tan) (credit:AP)
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A man takes a photo from the inside as a Greenpeace protester climbs up The Shard, the tallest building in western Europe, during a protest against the oil company Shell's drilling in the Arctic, Thursday, July 11, 2013. (AP Photo/Sang Tan) (credit:AP)
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Greenpeace protesters climbs up The Shard, the tallest building in western Europe, as a plane is reflected on the building during a protest against the oil company Shell's drilling in the Arctic, Thursday, July 11, 2013. (AP Photo/Sang Tan) (credit:AP)
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@GreenpeaceUK: Sabine & @victohenry clinging on as they attempt #iceclimb
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Go Liesbeth! #iceclimb Credit: Greenpeace
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Liam Jacquin
BO4GDIGCUAALaC(25 of42)
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Six women climbers start their ascent of the Shard, London's tallest building, for Greenpeace's Save the Arctic campaign.
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credit: Greenpeace
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Greenpeace activists begin to climb the Shard
London Aerial Views - Stock(30 of42)
An aerial view of The Thames in London showing The Shard building, Tower Bridge and Canary Wharf in the distance. (credit:PA)
London Aerial Views - Stock(31 of42)
An aerial view of central London including The Shard building and The City (right). (credit:PA)
London Aerial Views - Stock(32 of42)
An aerial view of The Thames in London showing The Shard building (right) and The City (left). The Olympic Stadium is also visible at the top. (credit:PA)
City Views - London(33 of42)
General view of the Shard building, London (credit:PA)
London Aerial Views - Stock(34 of42)
An aerial view of The Thames in London showing The Shard building, Tower Bridge and Canary Wharf in the distance. (credit:PA)
Greenpeace protest at the Shard(35 of42)
Onlooker watch a group of six women Greenpeace activists as they climb the Shard in central London, in protest at drilling in the Arctic. (credit:PA)
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Reflected in a nearby building, Greenpeace protesters climb up The Shard, the tallest building in western Europe, during a protest against the oil company Shell's drilling in the Arctic, Thursday, July 11, 2013. (AP Photo/Sang Tan) (credit:AP)
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People watch Greenpeace protesters climb up The Shard, the tallest building in western Europe, during a protest against the oil company Shell's drilling in the Arctic, Thursday, July 11, 2013. (AP Photo/Sang Tan) (credit:AP)
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People watch Greenpeace protesters climb up The Shard, the tallest building in western Europe, during a protest against the oil company Shell's drilling in the Arctic, Thursday, July 11, 2013. (AP Photo/Sang Tan) (credit:AP)
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Greenpeace protesters climbs up The Shard, the tallest building in western Europe, as a plane is reflected on the building during a protest against the oil company Shell's drilling in the Arctic, Thursday, July 11, 2013. (AP Photo/Sang Tan) (credit:AP)
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A man takes a photo from the inside as a Greenpeace protester climbs up The Shard, the tallest building in western Europe, during a protest against the oil company Shell's drilling in the Arctic, Thursday, July 11, 2013. (AP Photo/Sang Tan) (credit:AP)
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One of six Greenpeace protesters climbs up The Shard, the tallest building in western Europe, as workers look from a window, during a protest against the oil company Shell's drilling in the Arctic, Thursday, July 11, 2013. (AP Photo/Sang Tan) (credit:AP)
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Greenpeace protesters climbs up The Shard, the tallest building in western Europe, during a protest against the oil company Shell's drilling in the Arctic, Thursday, July 11, 2013. (AP Photo/Sang Tan) (credit:AP)