Officers said early on Tuesday morning that 20 males and 15 females, aged between 16 and 22, were released under investigation.Two 18-year-old men and two boys aged 16 and 17 were released on bail.One witness, who asked to remain anonymous and covered half her face with a scarf, claimed she had seen the victim being tended by paramedics.She said: “I was looking out of the window. I heard a man saying ‘leave him, leave him’ and then ‘get him’, and the person who must have done the stabbing shouting, ‘come on then, come on then’.“Then I heard someone say, ‘no, don’t do it’. It was a girl’s voice. She was the only one talking sense there.” Dozens of suspects were arrested after party-goers allegedly refused to cooperate with policeCredit:Mason El Hage Police were first called at 1amCredit:@koshmiah Want the best of The Telegraph direct to your email and WhatsApp? Sign up to our free twice-daily Front Page newsletter and new audio briefings. “I started to cry because I just couldn’t believe it – there is one man and there is 30 of [them].” A year of bloodshed on the streets of London was rounded off by the dramatic arrest of 39 people in connection with a stabbing on Monday.Police took the unusual step of detaining dozens of suspects at a house party in the early hours of New Year’s Eve, after being met with a wall of silence about the attack, which happened nearby.It was thought several assailants had chased and knifed a man outside a branch of Sainsbury’s, before running to the flat on Greyhound Road, Hammersmith, which was yards away.The victim, believed to be in his mid 30s, was taken to hospital where he remained in a critical but stable condition last night.Scotland Yard said the violence started with a “minor argument” in a shop on neighbouring Fulham Palace Road. Witnesses described seeing about 50 police officers, including dog handlers, arrive at the party at around 1am. They marched the occupants out of the building in single file and lined them up for questioning against a wall. The woman said she had seen the group run into the building, where someone allegedly kept watch through a window.“I made a call to the police, I said someone is going to get stabbed and at that moment that man got stabbed,” she said. “I was then on my way to my boyfriend’s house. As I got to the corner I saw the guy on the floor and he was stabbed right here [slightly below the chest].“He was in some burgundy boxers. He was breathing and paramedics were around him. I could see he was skinny. Forensic teams arrived to examine the flat on Greyhound Road on Monday afternoonCredit:Guilhem Baker/London News Pictures “Whilst it is unusual for so many people to be arrested in the early stages of an investigation such as this, due to a lack of cooperation and the necessity of securing essential evidence following a serious assault, this action was appropriate,” said Supt Mark Lawrence. Mason El Hage, a 23-year-old graphic designer who lived in the flat next door to the party, said he initially thought that the police were carrying out a drugs raid. He said: “Three riot vans rocked up and about 50 police officers marched up the road, went into the address next door and brought around 30 to 40 people and lined them up against the wall.“They were interrogating them for around an hour. They were young males, females.”Mr El Hage described it as a “very, very swift operation”.All suspects were arrested on suspicion of attempted murder and taken to several police stations. Officers recovered two blades close to the scene. Knife violence cast a long shadow over the capital last year, as politicians faced mounting pressure to bring the epidemic under control.Scotland Yard confirmed there had been 134 homicides in 2018, the highest number in London for a decade and a 13 per cent increase on the total for 2017, when there were 118, excluding the London Bridge and Westminster terrorist attacks. There were 110 homicides in 2016.