Seven of the minibus' occupants had returned home safely to Brighton after the minibus broke down at junction 18 on the M1.
Following an AA phone call the remaining six travelled in the cab of the recovery vehicle, owned by recovery firm Dunchurch Motors, along with the 46-year-old driver from Rugby.
The fatal collision killed all but one of the cab's occupants. The only survivor of the crash is currently in a stable condition in East Surrey hospital with a broken leg and facial injuries, Surrey police said.
The five passengers who died in the incident were all males aged between 25 and 35 from Brighton.
"This is one of the worst collisions that Surrey police have dealt with on the M25," Chief Superintendent Rob Price said.
"At this stage it is too early to confirm exactly what happened. A thorough investigation is being undertaken and it will be a number of days before we are in a position to release further details.
"Our thoughts are very much with the families and friends of the six people who died," he added.
Wreckage strewn across the motorway resulted in the London orbital being completely closed in an anticlockwise direction between junctions eight and nine, reopening at 11:30 BST today.
Dunchurch Motors released a statement saying the incident was 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."
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