SASKATOON -- Humboldt Ambulance and STARS Ambulance took four people to hospital Wednesday after a head-on collision on Highway 5 west of Humboldt, RCMP say.

One man had to be extracted from the wreckage, according to a news release.

The two drivers, both men, remain in hospital in Saskatoon with serious injuries.

One other man is also hurt and remains in hospital.

A boy has been released.

The investigation continues.