The victim, in his early twenties, was hit in the chest from close range.
He was found by officers on the pavement outside the Green Man in Coldharbour Lane, and taken to King's College hospital, where he was pronounced dead.
A post-mortem examination was due to be carried out yesterday, and further details about the victim were withheld until he had been formally identified.
Detectives appealed to anyone who may have seen the incident to contact police. A Scotland Yard spokeswoman said: 'There would have been a lot of people in the area at the time.
'The Green Man pub has a licence until 2am.'
The scene was sealed off as forensic science experts searched the area.Reuse content