A teenage schoolboy was fighting for his life after being stabbed more than 20 times in a terrifying attack.
The 15-year-old was repeatedly knifed on a residential street in Luton, Bedfordshire in the early hours of Tuesday morning.
Locals described being woken by blood curdling screams that they said sounded like an animal in distress.
Bedfordshire Police said they had more than 30 officers working on the case, but were appealing for anyone who may have been in the area at the time to come forward with information that might help lead to the capture of the attacker or attackers.
Detective Inspector Jerry Waite said: "The victim received more than 20 stab wounds in this shocking incident and is now fighting for his life.
"It's absolutely vital that anyone who has any information about this incident, no matter how minor it may seem, gets in touch with us.
"You could help us find the person, or people, responsible for this horrific attack."
Kaycee Andrews, 18, who lives close to the scene said: "We have got woods at the back of us and you often get animal sounds in the night like foxes and even cats.
"That's what I thought I was hearing at first, an animal. But then it changed and it sounded like an adult scream. There was real pain in the scream. I broke off from my phone and concentrated on what I was hearing.
"It went quiet for a short moment and then the screams started again. This was someone screaming for his life. Its horrible to think he must have been going through something so horrible when I heard him screaming."
Another local said there had been gang tensions in the area, but police said they were maintaining an open mind as to the motive of the attack.
The stabbing came on a day when a sculpture was unveiled on the steps of Luton Town Hall made up of knives seized by the police in the battle against knife crime which now blights many towns and cities across the country.