A murder enquiry has started after a 21-year-old man who was injured in a fight died in hospital.
The man, who has not been named, was attacked with baseball bats in Leagrave Road, Luton, Bedfordshire on Sunday.
He was taken to Luton and Dunstable Hospital by ambulance, but the Luton man later died.
Det Ch Insp John Giles called the attack a "serious and violent assault".
Anyone with information has been asked to contact Bedfordshire Police.
Det Ch Insp Giles said: "I am actively appealing for anyone who saw what went on, or can shed light on what prompted the vicious attack to contact the police as a matter of urgency."
Police said the incident began in Leagrave Road, Luton at 2110 BST when two cars being driven by "opposing groups" collided at the junction with Dane Road.
The occupants of a silver Ford Mondeo then got out of the car, armed with baseball bats and attacked a group who were in an orange VW Golf.
Three of the occupants managed to escape the beating, but the 21-year-old victim was badly beaten.
The offenders got back into the Mondeo following the assault and drove off.
The car was found 40 minutes later on fire in Abigail Close in Luton.