Detectives believe two cars were driving in the Railton Road area of Brixton on Sunday when one of the cars hit a moped before crashing into parked vehicles.

A man from the car involved in the crash got out of the vehicle and was chased by a male, carrying a gun, from the second car. The fleeing male was shot and died at the scene.

The gunman then returned to his car and fled.

The moped rider also died at the scene as a result of his injuries.

Witnesses described hearing 12 shots being fired as the violence erupted on the busy street shortly before 8pm.

An investigation by the Metropolitan Police's Specialist Crime Command is now under way.

Officers are confident they know the identities of both victims, who were in their 20s, and their next of kin have been informed.

The moped rider was reportedly a delivery driver on his last call out of the day.

Fellow delivery driver, Paulo Silva, said he knew the victim, describing him as a "good boy" who was hoping to go to Brazil next month.

Smashed cars, an overturned moped and an abandoned bus could be seen this morning as police cordoned off the area to conduct forensic investigations.

Officers remain in the area and locals have been told to expect to see an enhanced police presence in the area.

Chief Superintendent Colin Wingrove of the Central South Command Unit, responsible for policing Lambeth and Southwark, said: "I am shocked and saddened by this incident.

"Our thoughts are with the families and friends of the two young men who have tragically lost their lives.

"We are supporting specialist crime detectives, who are working at pace to confirm the specific sequence of events and identify and arrest those responsible.

"I would urge anyone with any information however small to come forward to help bring whoever is responsible to justice."

He later said "there is nothing to indicate" the moped driver "was an intended target".

He added: "Tragically we believe that he was out riding his moped when he was caught up in this violent incident."

Anyone with information is asked to call police via 101 quoting reference CAD 6166/30Oct. To remain anonymous call Crimestoppers on 0800 555 111.

The latest violence means four people have been killed in two shootings in five days in the capital, after a separate incident in Ilford, east London on Tuesday left two men dead and a third injured.