Police are investigating after a teenager was shot and three men wearing balaclavas, one carrying “a big double-barrel shotgun” were seen seen fleeing the scene.
Emergency services were called after gunfire was heard near to Lambeth Town Hall, Brixton Hill, at around 7.15pm on Thursday.
Officers at the scene found a person in their late teens who had been shot and after being rushed to hospital his current condition is unknown.
One witness told MyLondon: "We just saw three men running down the road, there was one guy with a gun - there was three of them.
"They all had balaclava masks. One of them had a big gun under his jacket. He was at the back and had the gun hidden. It was a double-barrel shotgun, a big gun. The first one was looking back to make sure they were following. They ran towards Brixton station."
After people heard the gunshots, they took cover, the witness said.
They added: "These two old ladies with a baby started screaming 'I do not want my baby around this', so we ran and hid in a pub around the corner. The owner of the pub asked 'do I need to close the pub?'."
One witness passing by on a bus, said: "The bus stopped and we heard then saw this big silver 4x4 crash and there were these guys running out of it, Then we heard six gunshots and a guy with a rifle ran by the bus. It’s the first time I’ve ever experienced something like that.
"The reactions that people [....] we were ducked down some crying and shaking.
"[The bus] was probably about 70/100 meters away. It was pretty loud and you could tell straight away what it was - a car crash then multiple gun shots.
"Our bus was stopped when it was happening, then I crouched down for safety."
The Met has said a crime scene remains in place and the road is closed to traffic.
There have been no arrests and a spokesperson for the Met police said: "Police were called at about 19:15hrs on Thursday, 12 May to reports of a firearm discharge on Brixton Hill, SW2.
"Officers attended and found a man, believed to be aged in his late teens, suffering from a gunshot injury. He was taken to hospital by the London Ambulance Service; we await an update on his condition.
"A crime scene remains in place and the road – at the junction with Effra Road – is closed to traffic. At this early stage, there have been no arrests and enquiries continue."
Anyone with information is asked to call police via 101 quoting reference CAD 6825/12May.
