Horrified residents have described seeing armed police swarm their block of flats moments before officers shot dead a man who had a gun and was threatening to kill someone.
Police were called to an address in Cedar Road, Enfield, north London, at 11.50pm on Sunday.
They shot a white man outside a flat on the sixth floor of Picardy House, a 12-storey former local authority building near Lavender Hill cemetery.
Scotland Yard said the man, who is believed to be 43 and has not yet been identified, was pronounced dead at the scene and a non-police firearm was recovered.
A Metropolitan Police spokesman said: "No arrests have been made. There are no other reported injuries."
Neighbours described seeing around 20 armed officers enter the building before hearing two shots that "sounded like firecrackers".
Residents said the shooting happened outside a flat on the sixth floor which was cordoned off as police carried out a forensic examination of the scene.
Dowan Mustafa, 20, who lives on the seventh floor with his mother, said he saw armed police officers swarm the building shortly before midnight and later heard two shots being fired.
He said: "I was looking over our balcony and I saw coppers swarming the building. They were armed - around 20 of them.
"The coppers came in and after I heard the shots.
"I heard two gunshots, proper loud gunshots, which woke everyone up.
"They are saying it was a shotgun but we are not too sure.
"Everyone has been evacuated from the sixth floor."
Scotland Yard said officers were called to an address in Barnet, north London, on Sunday night following reports that an armed man was making threats to kill.
Police went to the property at 9.35pm but he had left before they arrived, and armed officers later went to Picardy House.
A body was removed from the building on a stretcher at around 1.50pm on Monday and driven away in a private ambulance.
Locals said they were "horrified and appalled" at the shooting, adding that there was little trouble in the area.
Residents described seeing scores of police and ambulances outside the building on Sunday night while armed officers hunted for the man.
While some neighbours said they heard two shots, others thought it could have been as many as four.
Richard Nyarko, 48, who lives on the eighth floor of Picardy House with a flatmate, said: "I was lying down talking to someone back home in Ghana.
"I heard a noise - three or four shots, definitely three or four.
"After about 20 minutes I came out on to my balcony and saw armed police outside the front entrance. They had their guns drawn and were all over the place.
"Within five minutes I heard one of them say 'We have located him' and I saw paramedics and the police rush to where he was.
"I have lived here for almost 11 years and I feel the place is getting a bit rough."
Bob Mallick, 62, who lives on the fifth floor with his wife and daughter, said he first thought the gunfire was the sound of firecrackers being set off.
Mr Mallick, a lecturer at Capel Manor College in Enfield, was with his daughter and her boyfriend when they heard "loud bangs".
He said: "We were just having a cup of tea and coffee and we heard these two loud bangs - 'Bang, bang, bang' - and then there was a shot then after that.
"The first thought was firecrackers because we are getting close to November and kids are buying firecrackers already, but the shot kind of belied that a bit.
"There were lots of armed police with guns everywhere and there were helicopters overhead."
Mr Mallick said he was "shocked and appalled" by the shooting, adding: "This kind of thing never happens here. We don't run around scared, the place is full of hard-working families.
"The one thing I don't want anyone to think is that this in any way is a dysfunctional or troubled, menacing or threatening, scary neighbourhood to live in.
"We don't even get muggings here. Old ladies can go out at midnight and someone will help them across the road."
A post-mortem examination will take place on Tuesday.
Scotland Yard's Directorate of Professional Standards also attended the scene, and the incident was referred to the Independent Police Complaints Commission (IPCC) for investigation as a matter of routine, a Met spokesman said.
The IPCC is now investigating, and commissioner Cindy Butts said: "Fatal police shootings are rare but require thorough independent scrutiny when they do occur.
"Our investigators are gathering all of the evidence to understand the full circumstances of what happened."