The multi-vehicle crash began when a car crossed the centre line and hit a transport truck on Highway 16 near Valemount, B.C. ((RCMP))

Three members of a New Brunswick family were killed Monday in a six-vehicle crash on Highway 16 west of Jasper, Alta.

RCMP have identified the victims as Katie McCullough, eight, her mother Tracy Lee Mowbray, 31, and her grandmother Shirley Mowbray, 53, all of Kilburn, N.B.

Allie Rosaleen McCullough, five, suffered serious injuries and was in stable condition in Children's Hospital in Edmonton, police said.

RCMP said the family was travelling west near the Tete Jaune, B.C., weigh scales when their car crossed the centre line and crashed into a transport truck at about 11:30 a.m.

The truck then veered off into a highway rest area, striking a motorcycle, which then hit pedestrian Jeff Anderson, 32, of St. Albert, Alta. He suffered a fractured leg and was taken to Edmonton for treatment.

The truck also struck two other vehicles and another motorcycle in the rest area. The driver of the transport truck received minor injuries and was treated and released.

RCMP Sgt. Pat McTiernan said investigators are trying to determine whether a medical condition or mechanical failure played a role in the crash.

"This type of crash, when it involved a small vehicle and a commercial transport truck, it doesn’t take much [to kill them.] It’s touched many people working on the case," he said.

"The investigators at the scene have expressed their feelings in that they’re looking at an entire family that has died in a car crash. That’s difficult to deal with sometimes."

The B.C. Coroner's Service is also investigating, and police are looking for witnesses.

The highway was closed for almost 10 hours during the investigation.