No children were on board and nobody was injured when a fire quickly spread through a school bus in Ottawa's south end Tuesday afternoon.

Ottawa firefighters were called to Dwyer Hill Road, near Purdy Road, when witnesses saw flames coming from underneath a school bus at about 3:30 p.m.

The school bus driver pulled the bus over when he noticed the flames and tried to put the fire out with an extinguisher.

By the time firefighters arrived, the engine and front section of the bus were fully engulfed in flames. Firefighters managed to extinguish the blaze quickly.

The cause of the fire is unknown.