Six people have been confirmed dead after an out-of-control bin lorry crashed in the heart of Glasgow today.
Witnesses described bodies lying in the road after the accident which happened as the city centre was crowded with Christmas shoppers.
One witness said the lorry hit people "like pinballs" and it is believed to have travelled around 300 metres between hitting the first person and stopping.
Police Scotland has declared a major incident and confirmed there were a "number of fatalities" over a "number of sites".
Superintendent Stewart Carle said at the scene that the lorry hit several pedestrians as it careered along the road: "I can't confirm how many fatalities there have been because it is over a number of sites."
Reports suggested the lorry first struck pedestrians queuing at the Gallery of Modern Art (GoMA) and then careered down the pavement around 300 metres to George Square.
A police statement said: "A Glasgow City Council bin lorry was traveling north on Queen Street when it appeared to strike pedestrians outside the Gallery of Modern Art before continuing to travel towards George Square, when it crashed at the Millennium Hotel on Queen Street at George Square."
According to the ambulance service, casualties are in double figures. Roads surrounding the area have been closed.
Seven people were seriously injured and taken to three Glasgow hospitals - the Southern General, the Western Infirmary and Glasgow Royal Infirmary.
The driver of the lorry has been taken to hospital and police are not treating the incident as criminal.
Witness Melanie Greg told Sky News the lorry travelled 150 yards along the pavement until it crashed into a building.
She said: "The bin lorry just lost control. It went along the pavement, knocking everyone like pinballs.
"There was a baby in a buggy, and it just continued knocking people down until it ended up in the building. Quite horrific, very scary.
"The only way it stopped was hitting the building.
"People were trying to run out of the way. But when something was coming out behind them like that, how can they run out of the way? It was such a horrific thing. Just horrible. You don't expect something to be coming along behind you like that to knock you over.
"There was noise, bangs, screams and everything. It was just horrific."
“People were darting all over, it was really traumatic for a lot of people," one onlooker told The Scottish Sun.
“In my mind, I was worried it was a terrorist attack."
Superintendent Carle sought to reassure people, saying: "It's a road traffic accident, nothing more sinister.
"We are currently starting a joint investigation with the criminal investigation department as to what has happened here this afternoon."
Witnesses say a garbage truck reversed onto a pavement in George Square leaving many in shock. pic.twitter.com/QVw0C8jbf7— Joty Chopra (@jotychopra123) December 22, 2014
Whole of George square is shut off, bodies on the road. Scary man pic.twitter.com/iYDw297wdl— Brett Molloy (@BMol14loy) December 22, 2014
Emergency services have set up a tent in George Square pic.twitter.com/n1TdhzyYdU— David Wyllie (@journodave) December 22, 2014
Student, Joty Chopra, 21, told STV: "I was a few feet of way at Di Maggios when I heard a big bang and some screams. I ran to see what was there. As I reached the hotel there was a lot of people gathered.
"The first thing I saw was two people on the floor with blood around them. One seems to have been hit in the jaw, blood was coming out of their mouth. The other was lying completely on the floor with a pool of blood around their head.
“Police sealed the air right after that. One woman who had a young kid with her fell to the floor and was being treated for shock.”
Eyewitnesses say the lorry collided with another vehicle before mounting the pavement.
Describing the scene on Twitter, Brett Molloy tweeted: "Something major has kicked off at Queen St.
"Holy shit this major, 2 Bodies on the road, traffic lights down the lot scary shit.
"Whole of George square is shut off, bodies on the road. Scary man.
"Horrible, horrible scenes. Even worse at this time of the year.
"City centre is an eerie, eerie place right now."
The city centre was packed with Christmas shoppers at the time. The lorry crashed into the side of the Millennium Hotel, which is next to the station.
Roads surrounding George Square were closed as emergency vehicles dealt with the aftermath.
Witness David Lyon was walking across the road with his girlfriend when he spotted the lorry coming towards them “out of control”.
He said: “I was quite literally walking across the road when I saw the garbage truck pretty much plough through people.
“Debris was getting thrown into the air.
“My first instinct was to pull my girlfriend out the way, it just happened so fast.”
Local cab drivers David Farrell offered to give people free lifts if they were stranded and needed to get home.
Ok Twitter do ur stuff. I'm working in town, any1 directly affected by 2days tragedy & cant get home or 2 hospital, i'll take them for free— David Farrell (@davidfarrellfaz) December 22, 2014
Restaurant owner George Smith told the BBC he had heard that the bin lorry driver had suffered a heart attack and the vehicle had careered along the street before hitting the pedestrians outside the Millennium Hotel.
He said that the emergency services were on the scene within minutes, adding: "It's really, really sad."
The Scottish Fire Service tweeted: "Firefighters are in attendance at a serious incident in Queen Street, Glasgow. Our crews are working alongside other emergency responders."
Comedian Janey Godley tweeted: "Utter horrific carnage people on ground getting triage street poles smashed into pavement emergency services all over it.
"Local shop keeper says bin lorry and taxi involved & lorry mounted pavement #georgessquare
"I was at G square in immediate aftermath it's not something I ever want to see again - wandered in with music on before tape went up."
John Maclennan @johnmaclennan tweeted: "Seeing injuries in Royal Exchange Square, bin lorry ran all the way up Queen Street into #georgesquare awful."
Scotland's First Minister Nicola Sturgeon said: "My thoughts with everyone involved in dreadful George Square incident. If you are in city centre, please let your relatives know you are OK."
Prime Minister David Cameron said: "I'm being kept fully briefed on the major incident in Glasgow. My thoughts are with the families of those involved and the emergency services."
Labour leader Ed Miliband said: "Terrible news from Glasgow - my thoughts are with all those affected by this horrific accident."
David Cameron tweeted that he was being kept "fully briefed" about the incident, adding; "My thoughts are with the families of those involved and the emergency services."
I'm being kept fully briefed on the major incident in Glasgow. My thoughts are with the families of those involved & the emergency services.— David Cameron (@David_Cameron) December 22, 2014
Police Scotland have set up a number for anyone who has concerns that their family and friends may be involved in the incident which is 01786 289070.
But Assistant Chief Constable Wayne Mawson said the line was being inundated with calls and asked those who may have concerned loved ones to phone them.
He said: "Due to the volume of calls that we are receiving, it would be helpful if anyone who was in Glasgow city centre today can call home to let their loved ones and friends know that they are safe."