A school bus full of students was involved in a morning accident that left one person dead, but none of the children hurt.

Police credit the bus driver with making the right defensive driving decisions just before 9 a.m. Monday morning when a car driving on Leslie just north of Queensville crossed the centre and slammed into the bus.

The school's principal extended thanks to the bus driver.

"We have a lot to say to our bus driver," Marion Knisely said. "Thanks so much for being such a good guardian of our children today."

The car, a red Mercury Sable, slammed head-on into the bus. The 30-year-old male driver died on impact. He is believed to be from the Barrie area.

A third car was also involved in the accident but the driver was not seriously injured.

None of the approximately dozen children on the bus, who are students at Queensville Public School, were injured.

Police do not know why the car's driver strayed across the centre line. When officers received the call, they prepared for the worst.

"It's a parent's worst nightmare," St. David Mitchell said at the scene.

"When I got the call this morning, I have kids, and the other police officers in the area, we have kids and the first thing that goes through everybody's mind is okay, 'how are the kids, is everybody okay, what's happened?'"

Police are investigating why the car's driver strayed across the centre line.

The stretch of roadway north of Ravenshoe was expected to remain closed for several hours.

Students were not told that the car's driver had died. That job was left to their parents. But trauma counselors were scheduled to be available at the school on Tuesday.

With a report from CTV's Chris Eby