Toronto police are appealing for witnesses to contact them as they investigate a crash that killed a TTC bus passenger and injured several others.

Of the potential witnesses, police want to speak to the driver of a transport truck that was in the area when the bus and a flatbed truck collided Tuesday afternoon.

Police said the transport truck driver may be a witness and may be able to provide some information that will be helpful to investigators.

The collision on Lawrence Avenue East, near Don Mills Road, killed a 43-year-old woman and injured at least 13 others. Of the injured, nine were taken to hospital for medical treatment.

The woman's name hasn't been released.

The front right side of the bus was torn apart when the vehicles collided. Police believe the bus was making a lane change when it struck the rear of the flatbed truck.

The investigation is being handled by the Toronto police traffic services unit, but the TTC is conducting its own internal investigation.

Anyone with information is asked to call police at 416-808-1900.