A mother whose two-year-old son died in a head-on collision has also lost her unborn baby, police said.
She and her husband remain in a critical condition in hospital.
A Polish man in his 20s was also killed in the high-speed crash in Torquay, Devon, on Friday afternoon.
The Vauxhall Vectra he was driving collided with a Volkswagen Golf carrying the family of three in Hamelin Way at 2.45pm.
A Devon and Cornwall Police spokesman said the 36-year-old mother and 39-year-old father, who are from Ireland, have undergone operations.
He said: "The male driver remains in intensive care in Derriford Hospital, Plymouth, and in a critical condition having undergone surgery. The 36-year-old woman, who was a front seat passenger, was initially conveyed to Torbay Hospital but later transferred by land ambulance to Derriford Hospital where she remains in a critical condition. The female casualty was pregnant and an operation was carried out to save the unborn child. However, the child did not survive."
The Polish man, who lived in Torquay, was arrested before being taken to hospital, where he subsequently died.
The road was closed for more than 10 hours while the vehicles were recovered and forensic examinations took place. A police major crime investigation team and serious collision investigation unit are both looking into the circumstances of the crash.
The crash was witnessed by a police officer who was immediately on the scene. Twenty-five emergency service vehicles attended the incident, along with three air ambulances, including one from Dorset, which helped to take all four occupants of the cars to hospital.
The spokesman said: "The weather conditions at the time were challenging, with heavy rain falling creating an extremely difficult working environment for the emergency services and was very traumatic for all involved. Family liaison officers have been appointed to support the families."