This sounds bad on several counts

From the Evening Standard:

Eyewitnesses described mayhem at Stockwell Tube station today after a suspected suicide bomber was shot dead fleeing from armed police. One said the man was shot five times as he ran on to a Northern line train soon after 10am. Scotland Yard have confirmed they shot a man and he was pronounced dead at the scene….

“As the man got on the train I looked at his face. He looked from left to right, but he basically looked like a cornered rabbit, like a cornered fox. He looked absolutely petrified. He sort of tripped but they were hotly pursuing him and couldn’t have been more than two or three feet behind him at this time. He half-tripped, was half-pushed to the floor. The policeman nearest to me had the black automatic pistol in his left hand, he held it down to the guy and unloaded five shots into him.

“He looked like a Pakistani but he had a baseball cap on, and quite a thickish coat. It was a coat like you would wear in winter, a sort of padded jacket. Maybe he might have had something concealed under there, I don’t know. But it looked out of place in the weather we’ve been having.”

I don’t know what the correct way to handle a suicide bomber is, so I’m not qualified to have an opinion on this. Perhaps I’ve seen too many movies, but it seems to me that if the guy was wearing a bomb vest, simply shooting him would run the risk of triggering a dead-man switch.

And if it turns out he wasn’t concealing a bomb, this would be truly appalling news.