The 17-year-old victims were shot inside the fast-food outlet in Brixton, south London, last Thursday afternoon.

Both were shot by a single gunman at close range, one in the chest and one in the arm. The latter was treated in hospital and discharged later on Thursday, while the boy shot in the chest is still in a stable condition in hospital, Scotland Yard said.

The shooting took place in front of terrified families and schoolchildren at the restaurant at the junction of Brixton Road and Coldharbour Lane.

It is believed the two victims had a brief argument with other people in the restaurant minutes before the shooting. After firing at the teenagers, the gunman is thought to have escaped on a bicycle along Brixton Hill.

The shooting is being investigated by officers from the Metropolitan Police's gun crime unit Trident.

A police spokesman said: "Trident officers investigating the shooting of two teenagers at the McDonald's restaurant in Brixton Road on September 28 have arrested two male youths in connection with the inquiry.

"Both males are currently in custody at separate south London police stations."

Detective Chief Inspector Andy Shrives, from the Trident team and leading the investigation, continued to appeal for witnesses. He said: "I would like to reassure any witnesses that the information they provide will be treated confidentially and professionally and we are committed to ensuring that witnesses and family members are supported and, if necessary, protected."

Any witnesses, or anyone with information that may assist the inquiry, should call Trident detectives on 020 8785 8580 or, to remain anonymous, Crimestoppers on 0800 555 111.