Abbotsford resident John Hollier was on his way for coffee at about 1 p.m. on Tuesday when he spotted smoke coming from a BC Transit bus on Montrose Avenue across from Abbotsford Community Services.
He stopped to check out the scene and saw a bus driver using a fire extinguisher to put out the blaze.
Hollier, who caught the scene on video, said that, next, the windows of the bus blew out and the rear interior of the bus was fully engulfed in flames.
Abbotsford Fire Rescue Service (AFRS) quickly arrived on the scene and extinguished the fire.
A BC Transit spokesman said the fire is reported to have started in the engine compartment of the out-of-service bus.
No one was on the bus at the time, and there were no injuries.
The incident is under investigation by BC Transit and AFRS.