Police are investigating the scene of a school bus yard where a fire fully engulfed four buses in Burlington early Monday morning.

Halton Regional Police said emergency crews responded to the First Student Bus Lines yard located at 5421 Dundas Street, between Tremaine Road and Sutton Drive, sometime after 4 a.m. Monday.

Nobody was injured but police said four buses were fully involved by the time they arrived. Fire crews knocked down the flames and kept them from spreading to nearby buses.

Police said they cannot say at this point whether the fire was suspicious in nature.