A bullet which hit a bystander in the stomach in an east London park was fired from outside the park, police have said.
The man, aged 27, was wounded on Saturday in London Fields, Hackney, during a festival.
The Metropolitan Police said there was a "disturbance between two groups of youths" following which two shots were fired.
No-one has been arrested over the shooting.
The victim, whom the police described as a "totally innocent", remains in hospital in a serious but stable condition. His injuries are not life-threatening.
"It's now known the shots were fired outside the park and one of the bullets entered the park and hit the victim," a statement from the Met said.
Ch Supt Steve Bending, Hackney's Borough Commander, said: "It would appear that there was a disturbance between two groups of youths and then two shots were fired, resulting in an entirely innocent member of the public being shot.
"This was a callous, reckless and brazen act, without any thought by those responsible."
He added that police had been targeting gang-related violence in the borough and 125 people had been arrested for offences including firearms possession, causing grevious bodily harm, drugs supply and robbery.
Three firearms were recovered during the crackdown.
Officers from Operation Trident are investigating the latest shooting.