RCMP said that 15 people were injured in a collision near Slave Lake on Saturday.
The collision happened around 1:30 p.m. 20 kilometers southeast of the town.
Investigators said they believe the bus had a mechanical malfunction that caused it to leave the road and enter a wooded area.
Several of the injured were treated on the scene and others were taken to a nearby hospital with minor injuries.
The highway was closed for about an hour but was open again by 2:30 p.m.
Police say alcohol was not a factor.
