Five of the six people who died in one of the worst crashes on the M25 in 20 years had been returning from a stag event in Leicestershire, police say.
It took more than an hour to free the injured man from the wreckage
The group from Brighton were in a rescue truck which was carrying their broken-down minibus when it collided with a lorry between junction 8 and 9.
The recovery vehicle driver, who was 46 and from Rugby, died at the scene but the HGV driver was uninjured.
A sixth occupant of the minibus was also hurt but is stable in hospital.
Surrey Police said one of the occupants called the AA after the minibus broke down at Junction 18 on the M1.
Truck 'set up safely'
Seven people were picked up and returned safely to Brighton by one recovery vehicle from Dunchurch Motors Ltd.
The minibus was put on a second recovery vehicle and six members of the stag party group travelled in the cab with the driver.
The five Brighton men who died were aged between 25 and 30, police said.
The groom was not involved in the crash.
The one surviving person was taken to East Surrey Hospital in Redhill with a broken leg and face injuries - it took emergency services an hour to free him from the wreckage.
Surrey Police has confirmed that the recovery vehicle was set up safely to seat seven people - one driver and six passengers - with proper seat belts.
"This cab was configured to seat two passengers in front with a driver and four passengers behind," a spokeswoman said.
The crash happened at about 0215 BST near Reigate and the motorway was closed for several hours but reopened just after 1100 BST.
The cab of the recovery vehicle was completely destroyed in the accident, which left wreckage strewn across both carriageways.
The lorry driver was unhurt and is being treated as a witness by police.
Ch Supt Rob Price said: "Our thoughts are with the families and friends of the six people who died in this tragic crash.
"This is one of the worst collisions Surrey Police have dealt with on the M25."
Police have said it is too early to confirm the cause of the crash which is under investigation.
Dunchurch Motors Ltd, who are based in Rugby, issued a statement which said: "This is a terrible tragedy. We are trying to come to terms with this ourselves.
Our thoughts are with the family of our driver and the families of those affected by this tragic incident."
They said they could not comment further while the investigation was ongoing.
Police expect to identify the people who died on Tuesday.