A male pedestrian is in hospital with life-threatening head injuries after being hit by a school bus in Ottawa's east end late Thursday morning.

Paramedics say the 50-year-old man didn't have vital signs when they arrived at the intersection of Russell Road and Haig Drive just before 11:30 a.m.

Emergency personnel were able to revive the man and transported him to hospital where he is in critical condition.

The female driver of the school bus and three children on board were not injured during the collision.

Russell Road between Industrial Avenue and Smyth Road was closed for four hours while police combed the scene.

Police are continuing their investigation.