A man armed with two knives was shot dead by police in Westminster after three Tasers were fired.
The Independent Office for Police Conduct (IOPC) watchdog is investigating the incident, which is not being treated as terror related.
Investigators said two Ministry of Defence Police officers, who were on patrol, were told a man was acting suspiciously near Royal Festival Hall on London’s Southbank at around 11.35pm on Sunday.
He failed to stop and they radioed for back-up after firing a Taser, warning he was carrying knives.
The man is believed to have come across Hungerford Bridge before entering Northumberland Avenue, where Metropolitan Police officers fired another Taser.
A third Taser was fired before he was shot dead by a City of London Police officer after two of the force’s armed response vehicles arrived on the scene.
Forensic investigators were at the scene, where two knives were recovered, in Great Scotland Yard on Monday – a road that connects Whitehall and Northumberland Avenue, near Trafalgar Square.
It skirts the Department of International Trade, contains the Civil Service Club and various hotels and bars, and is about half a mile from the Metropolitan Police headquarters at New Scotland Yard.
The nearby area between Downing Street and the Houses of Parliament is the most heavily covered part of the country in terms of armed officers.
Joe Dunne, deputy manager of The Clarence pub, on the corner of Whitehall, said the incident was “not a complete surprise”, given the central London location.
Mr Dunne, 39, from Brixton, south London, said staff had closed the pub around an hour before the shooting.
“It’s not a complete surprise – due to the location, this can happen,” he said.
“It’s quite rare, I haven’t been around when that’s happened before – this means it’s fairly serious. If the police have shot someone, it’s fairly serious.”
Following the shooting, London Ambulance Service were called but the man was pronounced dead at the scene a short time later.
The IOPC is investigating, as is standard for any police shooting.
London Regional Director Sal Naseem said: “Our thoughts are with all of those affected by this tragic incident.
“Our investigators are working hard to secure evidence to establish the sequence of events which resulted in this man’s death.
“It is mandatory for the IOPC to conduct an independent investigation when the police fatally shoot a member of the public.
“We believe we know the identity of the man but his next of kin are still to be notified. In these circumstances it is for the police to notify the man’s family after which we will take over family liaison responsibilities.
“We have identified a large amount of relevant CCTV and many of the officers involved were wearing body-worn video. Over the coming days we will be retrieving and analysing that evidence.”
Fatal police shootings in the UK are rare and recent incidents have mainly been part of responses to terror attacks.
In the year to March 2019, there were 20,186 police firearms operations in England and Wales, around a quarter of which were carried out by the Met.
There were 13 incidents nationally in which officers actually fired their guns.
The most recent fatal shooting involving a Met officer and not linked to counter-terrorism was in April 2018, when Richard Cottier, 41, who was seen with a gun, was killed in Collier Row, east London.
Chairman of the Metropolitan Police Federation Ken Marsh called on the IOPC to conclude its investigation quickly.
He said: “While we understand and appreciate incidents such as this must be fully investigated, we call on the IOPC to bring this matter to a swift conclusion.”
Mr Marsh said the officers involved have the full support of the federation, which represents officers from the rank of constable to chief inspector.
“Once again, this incident shows our brave colleagues running towards and confronting a fast-developing, dynamic and dangerous incident, protecting the public at all hours.
“It’s what police officers do. We are the best of the best.
“Who knows how this incident could have ended – it could have been catastrophic. The public should be very proud that they have a police service – and heroic officers within it – that keep them safe.
“Our thoughts are with our colleagues as they now go through the post-incident process, and it goes without saying that they have our full support.”