An eyewitness has told LBC radio he saw two men attacking a man, aged around 20, with kitchen knives before asking passers-by to take photographs of them.
He told the radio station: "These two guys were crazed. They were just animals. They dragged him from the pavement and dumped his body in the middle of the road and left his body there."
He said that after the "horrendous" attack, the two men, in their 20s, just stood around, waving knives and a gun, even asking people nearby to take pictures of them "as if they wanted to be on TV or something".
"They were oblivious to anything, they were more worried about having their photo taken, running up and down the road," he said."They had no intention of running off or leaving or anything.
"It's horrendous what they were doing to that guy."
Some "brave" women tried to shield the man on the ground from them, he added.