A teenager stabbed to death after a party in south London has been named as Peter Hagan.
Hagan, 16, was knifed in the stairwell of a block of flats in Wandsworth. According to reports, the college student was attacked after leaving the party in Albion House.
His death came three years after his cousin was stabbed to death in a south London club.
Scotland Yard said a string of arrests were made in the hours after Peter Hagan's killing, which happened on Saturday.
He the fifth teenage victim of fatal violence in London in this year alone.
Hours before his death, a 19-year-old man was gunned down in Clapton, east London. Joseph Burke-Monerville was blasted as he sat in a car with his twin brother.
Devastated relatives of Peter said the teenager was "popular and funny".
One relative, who was not named, said: "The fact that he is gone hurts so much. I cannot believe I will not see him again. Sad is too good and upset is too nice a way to describe what I feel. To know that he is not going to walk through that door again - it's so upsetting.
"It is painful to think that somebody had the intention to kill him. It was not meant to be him.
"He was really excited about his evening," she added. "He was going to try to go to three parties. The one in Wandsworth was the second one. He was going to come and meet me later but he never came."
Peter's mother was "devastated" by his death.
DCI Nick Scola said: "I believe the victim had attended a party in Albon House. I need to trace everyone at that party, and in particular I am appealing for any information about a group of between five and eight males seen running from the scene into the surrounding streets and possibly through King George's Park."
In 2009, Peter's cousin, Carl Asiedu, was knifed to death in a nightclub in Vauxhall, south London.
Information can be passed to police on 020 8721 4005 or anonymously to Crimestroppers on 0800 555 111.