A team of more than 50 police officers are working on a murder inquiry into the death of a 22-year-old man in an apparently motiveless attack.
Sean Barwick was found lying in a road with serious head injuries
Sean Barwick, 22, was found with serious head injuries after being attacked as he walked home after a night out in Bridgend on Friday.
Police have said a motorist found Mr Barwick as he lay unconscious in a road in the Wildmill area of the town.
Three young men were being questioned by police on Monday about his death.
Det Supt Adrian Hogg, who is leading the inquiry, said that the those being questioned are thought to be part of a gang of about six to eight people who he wants to trace for questioning.
"Sean went into Bridgend town centre on Friday night and he went to Sax night club. He left there around one o'clock," he said.
"We don't have any other sightings of Sean until he was found at 3.25am."
It is thought he was walking through the Wildmill area as part of a local route from the town centre to Bryncethin when he was attacked and found in St Andrew's Road.
"Sean was a distinguished man - he was about 6ft tall with vivid ginger hair," said Det Supt Hogg.
"We want to find out who did he leave Bridgend town centre with if anyone - as far as we know it was on his own.
"It appears to be a motiveless attack."
A motorist found Mr Barwick in St Andrew's Road in the town
He said three young men were being questioned by police about the attack on Mr Barwick - two are from the Wildmill area and one from Porthcawl.
"We think that these three are part of a group of about six or eight and we are trying to establish what happened with the group," he added.
"Sean's family are devastated - he comes from a large family.
"We cannot establish a motive for why he was attacked - it was a particularly vicious attack, he received some serious head injuries."
Forensic science officers carried out a search of the area soon after he was found during the early hours of Saturday.
He died in hospital on Sunday at 1310 BST.
Police have issued an appeal regarding the gang they want to trace for questioning - three or four white males in their early-teens to late-20s.
They are also appealing for a man in his 30s or 40s, and two females with shoulder-length or long brown hair, who may have seen the victim walking home.
Mr Barwick was said to have been wearing a green Yves Saint Lauren polo shirt, blue denim jeans and white Velcro trainers.
Three young men, aged 17, 18 and 19, are being interviewed by police at separate police stations.
Anyone with any information is asked to contact the South Wales Police incident room at Bridgend on 01656 655555 or to contact their local police station.