Two men have been arrested on suspicion of murder after a 16-year-old boy was chased and stabbed with a machete in Camden.
Two of the attackers are said to be the teenager, named by the police as Alex Smith, has a third plunged foot-long blade into his chest and back in Munster Square, near Regent's Park.
On Wednesday, a 23-year-old man and an 18-year-old man were arrested on suspicion of murder. They remain in custody.
A post-mortem examination died from a stab wound to the chest.
Teenager banged on doors screaming "Help me, help me" During the attack at 11pm on Monday, we were told to go by terrified locals.
His death marks the 90th murder Scotland Yard so far this year. Fifteen of these teenage victims, 14 of whom were fatally stabbed.
Neighbors today told of the distressing scenes as the boy was pursuing the family home before being attacked.
Rosanara Begum, 55, said on Tuesday: "The boy was running away from them. Then we saw the two boys holding him and the other one stabbing him.
"As soon as I heard 'Help me, help me' I was on the phone to the ambulance. He was bleeding a lot.
"The attackers were skinny and just looked like teenagers. They were running off and they were screaming and laughing."
Her daughter added: "We saw three boys all wearing hoods all covered in black, the middle one had a long black machete type knife. It was really long."
Detective Inspector Jamie Stevenson said: "We're still keeping an open mind regarding the motive of this brutal attack and thank those who have come forward and spoken to us so far.
"We know there are people out there who can help this investigation and we continue to make contact with officers.
Please do the right thing and come forward, anonymously if need be, but do make the call."
Anyone with information that could assist the investigation is called to call 020 8358 0400 quoting Cad 8433 / 12Aug.