Police have arrested eight men after two teenage boys were killed in a suspected double murder in Brentwood, Essex.
Officers were called to Regency Court at approximately 1.30 on Sunday morning.
They found three injured teenagers, two of whom later died of their wounds. The third victim is being treated in hospital, where his injuries are not believed to be life threatening.
It is understood the victims suffered suspected stab wounds.
One neighbour reported hearing "shouts and screams" followed by "somebody yelling in pain".
Detective Superintendent Stephen Jennings said there was an altercation between "two groups" who "knew each other".
Essex Police are also investigating unconfirmed reports of an earlier altercation between the two groups.
Neighbour Mark MacIntosh said: "I came home last night, I came in five minutes before I heard the shouts and screams.
"I said should I go down as I usually do if I think there's something serious, but I couldn't hear.
"Now as I reflect what I heard was somebody yelling in pain who may have lost his life shortly thereafter."
He added that anti-social behaviour is a problem in the area, and that he urged police to step up patrols earlier this month.
“There's constant anti-social behaviour, drinking, drugs, shouting, fighting," he said.
"I've heard people saying 'I'm going to kill him' up there. I've broken up a knife fight down at the bottom here before.
"I phoned the police three weeks ago and told them you need to make constant patrols around here, because something bad is going to happen soon."
Essex Police Detective Chief Inspector Mark Barber said the incident was "probably a targeted attack" and isolated incident, adding there is no ongoing threat to the community and officers remain open-minded.
"We would like to appeal to anyone who was in the Crown Street area of Brentwood between 10pm last night and 5am this morning who witnessed any suspicious behaviour between that time frame," he said.
Detective Chief Inspector Andy Clarkson, of the Kent and Essex Serious Crime Directorate, said: "This incident has required an immediate and a large-scale response and officers and investigators have worked through the night to piece together what happened in the lead up to this tragic incident.”
On Sunday officers went door-to-door conducting enquiries, and are urging anyone with information to come forward.
Police said officers would maintain a visible presence over the next few days.
Specialist officers have been deployed to support the victims' families.
Family and friends of the victims laid flowers by the police cordon, many of the mourners visibly upset teenagers.
Alex Burghart, the Conservative MP for Brentwood and Ongar, expressed his horror at the incident.
"This is a very dark day for our town,” he said.
“My deepest condolences to the families of the boys who have so dreadfully lost their lives. I urge anyone who has information to immediately share it with the police, so that justice can be done as swiftly as possible."
“This is usually a safe area, you don’t expect this,” said Gareth Barrett, a Labour councillor for Brentwood South.
"My thoughts are with the families of the victims of this tragic incident in the heart of Brentwood Town Centre,” he said.
"This senseless violence is just horrific.
"We need to think long and hard about what we can do to make something like this never happens again."
Anyone with any information has been asked to contact Essex Police on 101 and cite incident 125 of October 24.