Police say it is unclear how Ben became involved in the disturbance
Police are continuing to question three teenagers who have been arrested in connection with the death of Ben Kinsella in north London.
Ben, 16, was stabbed to death in York Way, Holloway, on Sunday.
On Tuesday hundreds of people including family and friends marched through the area in protest at escalating knife crime among the young.
Ben is the 17th teenager to be killed in London since the start of the year. Three other men are on police bail.
They have been bailed to return to a police station in August while inquiries continue.
Speaking on Wednesday, Metropolitan Police Commissioner Sir Ian Blair expressed his sorrow at Ben's death.
He said Ben's stabbing showed "the problem of knife crime is still with us". "I know the communities of London understand that this is something they and the police have to solve together," he said.
"I promise that the Met is in this for the long haul and will do everything in its power to stop these murders continuing."
The Metropolitan Police said the three of the arrested men, two aged 18, and one aged 19, were detained this week.
One 18-year-old has now been bailed to return to a police station at a date in August. Two others are also due to return late in August.
The arrested men are being held at police stations in north and east London on suspicion of murdering the teenager who had just completed his GCSEs at Holloway School, Islington.
Protesters walked up to the scene where Ben was stabbed
At the march on Tuesday protesters wore T-shirts with Ben's picture bearing slogans such as "RIP Ben", "Stop Knife Violence", and "You're Always in Our Hearts".
Ben's three sisters joined the march wearing T-shirts showing pictures of him as a child and a teenager.
One of his sisters, former EastEnders actress Brooke Kinsella, said: "This is just another trial and another life lost.
"I want to say thank you to every single person who is here and everyone else thinking of him."
Birds of a Feather actress Linda Robson also joined the march with her son Louis who was with Ben after the attack.
She called for "stronger deterrents" to knife crime saying: "If you can do that to another human being, you are not going to be able to take that out by sending them to prison for five or six years."