Tommy Elmes, 16, and Tommy Marsh, 17, were among the four people killed
Three teenagers were among four people killed when their car left the road and hit a tree near Porthcawl.
The crash happened on the A4229 close to a golf club at South Cornelly, just before midnight on Thursday.
South Wales Police named the four as Tommy Elmes, 16, Tommy Marsh, 17, Danny Philbrow, 43, and Lewis Mackley, 19, all from Portsmouth in Hampshire.
A fifth person is said to be in a critical but stable condition at Morriston Hospital in Swansea.
Police said in a statement: "Early indications are that the vehicle, a silver-coloured Vauxhall Vectra, has lost control, left the carriageway and collided with a tree."
Golf professional Mark Rae, 23, arrived at the scene of the crash, which happened near Grove Golf Club, at the same time as an off-duty police officer who just happened to be passing.
Mr Rae said: "It was total devastation.
"I saw one lad crawling through the woods and it is a miracle that he escaped from the crash.
"I can't understand how anyone could have lived through that. It was complete carnage."
At first Mr Rae and the off-duty officer had thought that two cars had been involved, he said.
"But as I turned my own car around and put the headlights on full to alert other drivers, I realised it was two halves of the same car," Mr Rae explained.
"It had split into two and was smouldering after hitting a tree on the other side of the road to which it had been travelling.
"Part of it was down an embankment and another part was about 20 yards away with a tyre attached to it.
"When I got out of my car, the wreckage was smouldering and sparking and then it burst into flames."
The crash happened between Porthcawl and South Cornelly
Mr Rae said it appeared the car had crossed the opposing carriageway at speed, mounted the curb and headed down an embankment where it hit a tree.
"Goodness knows how fast it must have been going to have split the car in two," he said.
He said three of the people in the car appeared to have been thrown clear of the wreckage by the impact of the crash.
He was unaware at the time that more than three people had been involved until he was told later by the police.
Mr Rae also praised the professional approach shown by the off-duty police officer who arrived at the scene at the same time.
"He obviously knew what to do and thank goodness he was there because I wouldn't have known myself," he said.
"I stood and flagged down traffic and made sure than any on-coming cars could see us, but he took control of the situation."
Aubrey Green of Bridgend County Borough's highways department said the road had a clean record with no serious incidents recorded.
"This particular road has been upgraded in terms of safety in recent years," he said.
The men are believed to have been returning from a night out.
Anyone with information is asked to call the South Wales Police roads policing unit on 029 2063 3438 or the non emergency number 101 (if calling from Wales).