One appliance and crew from Gerrards Cross and two from Hillingdon, along with an officer attended.
A car was well alight.
Five men were out on arrival with minor injuries, passed into the care of South Central Ambulance Service.
The firefighters used two sets of breathing apparatus, two hose reels, a thermal imaging camera and an immediate emergency care kit.
There was a full motorway closure in place.
The incident was left in the hands of Thames Valley Police and the Highways Agency.
