Officers are appealing for information following the incident on the westbound A985 Limekilns to Rosyth road around 3.50pm on Sunday.
A blue Audi A3 and a silver Vauxhall Corsa collided at the scene, with the road closed for around seven hours while investigation work was carried out and the vehicles recovered.The male driver of the Corsa sustained serious injuries and a woman, the front seat passenger, minor injuries. Both were taken to the Royal Infirmary of Edinburgh.Two children, passengers in the back of the car, were taken to the Royal Hospital for Children and Young People in Edinburgh. A five-year-old girl sustained minor injuries and two year old girl was not injured.The driver of the Audi, a man, was not injured.Sergeant David Ross said: “We are appealing to anyone who may have seen what happened and has not already spoken to officers to get in touch. Anyone with dash-cam footage from around the time of the crash is also asked to contact us.“If you can help then please call us on 101, quoting incident number 1877 of Sunday, 26 December, 2021.”