A murder investigation has been launched after a 16-year-old boy was stabbed to death on Saturday evening.
The business student, Munashe Charles Kutyauripo, also known as Charlie, was murdered shortly after celebrating a friend's 16th birthday party at a social club at Ashton Playing Fields, in Woodford, northeast London, police said.
The teenager was thought to have got into "a confrontation" with four young men before he was attacked on the playing fields.
Guests at the party came to the victim's aid before police and paramedics arrived, the Met confirmed.
He was was taken to Whipps Cross Hospital, in east London, but was pronounced dead shortly after arrival.
Kutuyampo is thought to be the first teenager this year to be murdered in the UK's capital.
Police believe he was stabbed outside the social club by one member of the group, who then fled towards Chigwell Road.
The murder is being investigated by the homicide and major crime command units.
A postmortem examination to formally identify the body took place on Monday, which confirmed the cause of death as a stab wound to the chest.
On Sunday, forensics officers recovered one silver kitchen knife and one black-handled knife near the scene, however it has not been confirmed whether either was used in the stabbing, the BBC reported.
In a statement on Sunday, detective chief inspector Ken Hughes, who is leading the investigation, said: "There were around 100 young people at this party and we are appealing for anyone with information or any witnesses to come forward as soon as possible.
"The victim's family are naturally devastated and in shock by what has happened and we need the help of those at the party that night to progress our investigation."
There have been no arrests at this stage and enquiries continue.
Police have asked anyone with information to contact the incident room on 020 8345 3862 or Crimestoppers anonymously on 0800 555 111.