CALGARY — The driver of a school bus carrying three dozen children that collided with a minivan before running into a tree in northwest Calgary has been charged with driving carelessly and crossing over the centre line of the road.

Police say the driver was trying to pass the minivan on the left-hand side as it tried to make a left turn.

But an official with the company where she works said they were still investigating her claim the bus's brakes weren't working in the moments before the crash.

The driver of the minivan was also charged with driving with a learner's permit without supervision.

None of the children onboard the bus was seriously hurt when the two vehicles smashed last Thursday.

The impact of the collision flipped the van onto its roof in a residential driveway while the bus careened off the road and struck a tree on the front lawn of the same house.

Neighbours grabbed a crowbar to help frightened children escape from the back of the bus before emergency crews arrived. Seventeen children between the ages of five and 10 were taken to hospital with minor cuts and bruises.

Sgt. Graeme Ramsay said no mechanical problems were found with the bus and speed is not believed to be a factor.

"The collision occurred when (the driver) went into the opposing traffic lane to pass a vehicle that's turning left," he said Thursday.

"The bottom line is you can't do that when you're driving a vehicle."

Wayne Scadden, regional safety manager with First Student Canada, the company that owns the bus, said the company is waiting for the vehicle to be returned by the police so they can complete their own investigation.

He said the driver has been suspended since the crash and no decisions will be made on her future with the company until the internal investigation is completed.

"Her statement was she felt her brakes weren't holding, but the police cannot find that, they have cleared our bus of any mechanical failures."

Ramsay said all charges against the two women are under provincial traffic legislation and, if convicted, they could face fines.

The minivan's driver, 33-year-old Katherine Gamble of Calgary, is charged with driving with a learner's permit without proper supervision.

Bus driver Krista Donovan, 38, also of Calgary, faces a charge of failing to complete a daily inspection on her bus before setting out on the trip.