The family of a young man killed "like an animal" in a multiple stabbing attack on Halloween have appealed for witnesses to come forward.
Scott Kouebitra was stabbed along with three friends in an attack which lasted just 90 seconds in St George's Field Park in Croydon, south London, last Monday evening.
The 22-year-old, from Sutton in south-west London, was treated by paramedics but died shortly after 8pm just outside the park in Gloucester Road.
Three friends, aged 21, 27 and 22, were also knifed, while another man, aged 20, was injured after being beaten up.
Police are hunting for a group of around seven men wearing masks, scarves, balaclavas and/or hoods who made off toward St James' Road in two vehicles; one light, one dark.
Speaking yards away from the spot where his son died, Mr Kouebitra's father, Thierry, said: "If they don't find the perpetrator, then society is sending a very powerful and wrong message to the people who did it.
"Any one of us can sit in his home, make the decision to terminate the life of another one, walk into his kitchen get a knife and stab him and go back home freely. That's wrong.
"They need to find them, they need to hunt them, to find them. They are not doing it for my son, they are doing it for the other kids of Selhurst."
He went on: "We are not animals. That guy killed my son like an animal.
"We will rage in anger. He needs to pay for it. Please help me, help me to find him, because we can't afford to send this stupid message to everyone in society, because that's wrong."
Tributes for the young football fan, who was due to celebrate his birthday in two weeks, were left at the park gate and included an Arsenal hat, a French flag, and dozens of flowers and candles.
Mr Kouebitra's mother, Pauline, his older brother, Armele, oldest brother, William, and uncle, David, huddled together and sobbed as they read the messages people had left in his memory.
A post-mortem examination showed Mr Kouebitra died from stab wounds to the right side of his chest, the Metropolitan Police said.
No arrests have yet been made in connection with the attack, they added, as the family pleaded for anyone with information to come forward.
His older brother, Armel Nene, from Essex, said: "If there's not an arrest, nobody's coming forward to say why they did it ... we need to know why they did it.
"We will never be able to rest, if it took 10 years, 20 years ... I have no brother - my younger brother is gone now. When I wake up I'm dying inside, but my parents, they've gone through a lot worse than what I'm going through at the moment.
"They need to have some sort of lead," he added.
Mr Nene also called for CCTV to be installed inside the park, as police confirmed that a Croydon Council sign saying the area was CCTV-monitored was out of date.
He said: "There's a CCTV sign there saying there's CCTV in the park, so you have this false sense of security. I know they are trying to prevent it, but at the end of the day they need to prevent it entirely by actually having CCTV in case that when something does happen, we can catch whoever did it.
"They are relying on private CCTV from houses to try to find who did it, which I think is not right."
He said his younger brother, who recently turned 18 and was with Mr Kouebitra when he died, was too "destroyed" to leave the house.
Detective Chief Inspector Sam Price, leading the investigation, said: "The vehicles were here no more than 90 seconds, so it is my belief that the suspect group knew who they were looking for, and this was a targeted attack. But I don't know why, and I need people to tell me why."
She said that while Mr Kouebitra was not a gang member, she could not rule out the attack being gang-related.
She is specifically calling for a female passer-by who may have seen the end of the altercation as it spilled out of the park onto the street to get in touch.
Detectives from the Homicide and Major Crime Command continue to investigate.
Anyone with information is asked to contact the incident room on 020 8721 4054 or via 101, or Crimestoppers anonymously on 0800 555 111.