Firefighters say an engine malfunction may be what caused a double-decker bus to go up in flames Friday night.

Officials say it happened on Fifth Street and Oakville Avenue around 10:30 p.m.

The back of the BC Transit bus was fully involved when fire crews arrived.

Fire prevention officer, Darrin Blinko, says the fire started in the engine compartment, but it is technically undetermined.

Everyone onboard managed to make it out safely.