One appliance and crew from Beaconsfield, one from High Wycombe and one from Maidenhead attended, along with an officer.
One car was upright, and a second car was on its side, when they arrived.
The firefighters released one man and one woman, both injured, and passed the into the care of South Central Ambulance Service.
A second man was released, injured, before they arrived.
The incident was left in the hands of Thames Valley Police.