Police are investigating the possibility of a link between a drive-by shooting that injured four people and a stabbing in which a 33-year-old man was critically injured.
The shooting, which left a 25-year-old man in a life-threatening condition, happened on Coldharbour Lane in Brixton, south London, at about 01:15 BST on Saturday. About an hour later, Met Police officers were called to a stabbing some 700m away on Acre Lane.
Four people were taken to hospital with gunshot wounds after the shooting. Three people, aged 21, 47 and 70, received non-life-threatening injuries, the Met said.
No arrests have been made in connection with either attack.
Officers are investigating the possibility the two attacks are connected, the Met said.
A cousin of the 25-year-old man in a critical condition after the Brixton shooting told the BBC their family member was "just a civilian".
The cousin, who did not want to be named, said: "He's on a machine in hospital. They got four civilians here, he is a good person and not involved in gangs or anything like that."
The shooting happened in the early hours of Saturday when a car approached from the other side of the road and fired seven shots, a witness told the BBC. He said he saw a man being shot in the head.
The witness, who also did not want to be named, said people had gathered outside Southwyck House, Coldharbour Lane, on Friday evening to enjoy a barbecue, with families attending.
"People had just been enjoying the sunny weather… then they started scrambling and running away. There had been children there earlier, too."
The London Ambulance Service treated four patients at the scene, taking two of them to a major trauma centre and two to a local hospital.
On Sunday, about 10 forensics workers were seen sifting through material on Coldharbour Lane at the site of the shooting, which the BBC was told is often used to host barbecues. They were seen sifting through the debris of bottles, bags and other rubbish.
Det Ch Insp Allam Bhangoo, who is leading the investigation, called the shooting an "act of indiscriminate violence".
"We understand how concerning this incident will be for the local community and want to reassure residents that officers are working at pace to identify those responsible," Bhangoo said.
The man found on Acre Lane had multiple stab wounds and remains in a life-threatening condition, as does the man shot on Coldharbour Lane.
The police are appealing for anyone with information about either attack to come forward.
Moh John, 45, who works at a supermarket near Southwyck House, said the people who rushed into the shop after the shooting were scared and he kept the doors locked for "some time".
He told the Press Association (PA): "It was busy, there was a party. I saw the people run away.
"But then I saw the people, some people try to come in the shop and I locked the door."
Robert, 40, who did not want to give his surname, said he did not see the shooting but told PA: "I think it happened at the barbecue. It was packed.
"I usually feel safe around here, people know each other and get on. There's been a few stabbings, and one day one gun was caught, but I don't think anyone's ever been shot like this."
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