Investigations are underway into the school bus tragedy near Palmerston North

A bus driver was killed and six students were injured yesterday morning, when a school bus collided with a train at a level crossing at Bunnythorpe.

One of the first people on the scene has described seeing trapped students trying to smash windows to get out.

Transport Accident Investigation Commission spokesman Simon Pleasants says investigators have begun an inquiry, starting with an inspection of the bus, the train, and the crash site.

He says they will be mapping the site and examining the rail systems, including the crossing signals.

The commission's appealing for witnesses, particularly those who may have dash cam footage of the crash.