The identities of the victims had not been not released.
The accident on the Pacific Coast Highway, 3.5 kilometers (2 miles) north of the U.S. border with Canada, occurred Sunday when a minivan apparently ran a red light and collided with a mid-sized import car, Sgt. Dale Carr of the Royal Canadian Mounted Police in Surrey said.
"The import vehicle was completely sheared in half and is unrecognizable," Carr said.
A family friend told told the Canadian Broadcasting Corp. the five killed were three women and two children from the same family.
A man in his mid-40s was airlifted to a hospital in serious condition. Police said he is likely the driver of the minivan.