Two appliances and crews from Aylesbury attended, along with a rescue crew from Kidlington and two officers.
A man and a woman, both injured, had been travelling in one car. The firefighters used heavy rescue equipment to release them from the car while they were cared for by South Central Ambulance Service.
The second car contained one man, who was helped from the car by firefighters and the ambulance service.
Firefighters used two immediate emergency care packs.
Thames Valley Police also attended.