Detectives investigating the fatal stabbing of a teenage boy in north London have released two suspects on bail.

Nedim Bilgin, 17, died on Tuesday after being stabbed at least twice with a large knife on Caledonian Road, Islington, 300 metres from his home.

Two teenagers – a 16-year-old and a 17-year-old – arrested close to the scene on suspicion of murder were bailed to return to a police station in a month’s time, the Metropolitan police said.

An 18-year-old arrested at an address in Islington on Tuesday night, also on suspicion of murder, remains in custody.

Forensic tests are being carried out on knives recovered from near the scene to determine whether they were used in the attack and if they can be linked to any individual. A postmortem was due to take place on Thursday.

Nedim, 17, was pronounced dead within 30 minutes of the attack. Police have said his mother was alerted by locals and saw her son lying on the ground as paramedics tried in vain to save his life. He was the second teenager to die after a knife attack in London this year.

Ch Supt Nick Davies said two youths were arrested while running from the scene after locals who witnessed a clash between young people called the police.

Davies said it was too early to speculate on a motive for the stabbing, but he said: “A gang fight is a line of inquiry. He was attacked by a group of males and they ran away. There has been some sort of fight and this has happened.”

Davies said Nedim may have been chased, and police had seized video of the aftermath of the attack posted on social media.

He said police believed there may be witnesses who had yet to come forward. “Other young men were at the scene and saw what happened. The public need to do something more to help us.”

Nedim was the eighth homicide victim in London this year. There were 135 killings in the capital in 2018, an increase on the previous year.

Before Christmas, Nedim went missing for 10 days. That is believed to be the only time he previously came to police attention.

Police do not believe robbery was a motive. A bicycle was found close to the scene, and detectives are trying to establish to whom it belonged and whether the victim had been riding one before the attack.

Police were called at 6.49pm and by 7.15pm the teenager had been formally pronounced dead at the scene. The incident happened on Caledonian Road near the junction with Tilloch Street, close to a betting shop.

Data from the Ministry of Justice shows just under 4,500 knife or offensive weapon offences resulting in a caution or conviction were committed by 10- to 17-year-olds in the year to March last year. This was the highest number in eight years, but lower than the 6,446 offences in the year ending March 2009 and 4,626 in 2010.