TWO separate collisions in Canberra have left a woman with life-threatening injuries, and three others in hospital.

Police say a woman and child were injured when a red Suzuki Swift hatchback ran off the road and collided with a fence near Farrer yesterday (December 15).

They were taken to Canberra Hospital, with the woman suffering life-threatening injuries.

About 3.35pm yesterday police were called to another collision involving a pedestrian and motorcycle on Limestone Avenue, Reid.

Police say both people were taken to hospital with serious injuries.

Any witnesses or anyone with dash cam footage is urged to call 1800 333000.