Middlesex OPP are investigating after a fatal crash involving a school bus on 12 Mile Road and Adelaide.

Emergency responders were called to the crash Tuesday morning at 9:18 a.m.

Police say the bus was travelling westbound on Twelve Mile Road, when it struck the north side shoulder of the roadway.

It then travelled across the roadway, where the front of the bus slammed into a tree on the south side of the roadway, causing the bus to roll onto its passenger side.

The 63-year-old female driver was pronounced dead at the scene.

There were no kids on the bus at the time of the crash.

Her name is being withheld pending notification of next of kin.

Highbury Avenue at 12 Mile Road has since re-opened.