A man and a woman are in critical condition after their vehicle drifted into oncoming traffic and collided with a passenger bus in west Quebec Sunday night.

The couple was travelling on Highway 309 in L'Ange-Gardien at about 8:40 p.m. when they collided head-on with the bus, ripping off the front end of their car.

The car's engine became detached from the vehicle, causing it to fly several metres from the point of impact.

The bus driver was unharmed, and there were no passengers on the bus at the time of the collision.

Police say alcohol may have been a factor in the crash. However, the collision remains under investigation.