Quickly developing story as of now, first report from the BBC is below.
Man shot by armed police on Tube
A man has been shot at Stockwell Tube station by armed police officers.
Passenger Mark Whitby told BBC News he had seen an Asian man shot five times by "plain-clothes police officers" with a handgun.
Passengers were evacuated from the Northern Line station in south London. Ambulances including an air ambulance have been sent to the scene. Police have cordoned off surrounding streets.
Police are hunting four would-be bombers after Thursday's London blasts.
Services on the Victoria and Northern lines have been suspended following a request by the police, London Underground said.
The bombers fled after detonators went off, causing small blasts, but failed to detonate the bombs themselves.
Mr Whitby, told BBC News: "I was sitting on the train reading my paper.
"I heard a load of noise, people saying, 'Get out, get down'!
"I saw an Asian guy run onto the train hotly pursued by three plain-clothes police officers.
"One of them was carrying a black handgun - it looked like an automatic - they pushed him to the floor, bundled on top of him and unloaded five shots into him.
"I saw the gun being fired five times into the guy - he's dead."
Passenger Briony Coetsee said: "We were on the Tube and then we suddenly heard someone say, 'Get out, get out' and then we heard gunshots."
http://news.bbc.co.uk/1/hi/uk/4706787.stm