One appliance and crew from Beaconsfield, one from Slough and one from Gerrards Cross attended, along with an officer.
Two men were out, injured and being cared for by South Central Ambulance Service when the firefighters arrived. One girl was out, uninjured, before they arrived.
The firefighters provided immediate emergency care, and used hydraulic rescue equipment to rescue one man and two women, all injured, who were passed into the care of the ambulance service.
The motorway was closed while they worked at the scene.
Thames Valley Police also attended.
