One person is dead and four others have been injured, including three children, in a head-on crash in southwestern Ontario.

Police said it happened on Hofstetter Road in Blandford-Bleinheim Township, southwest of Kitchener, just after 1 p.m. on Monday.

Ontario Provincial Police Const. Ed Sanchuk said a northbound SUV and a southbound vehicle collided for unknown reasons.

The driver of the southbound vehicle suffered life-threatening injuries and was transported to a local hospital, where he was pronounced dead, Sanchuk said.

Meanwhile, the occupants of the SUV – a man and three children – were also injured in the collision.

The man and two of the children were taken to a hospital with non-life-threatening injuries, Sanchuk said, adding that the third child was airlifted to a hospital in non-life-threatening condition.

The cause of the crash is unknown.

Sanchuk said police are looking to speak with the driver of another vehicle, who may have been in the area at the time of the collision.

Police have closed Hoffstead Road between Township Road 14 and Oxford Waterloo Road.

Sanchuk said the closure is expected to last until late Monday evening while police investigate the circumstances surrounding the crash.