Two adults and two children with extremely severe burns were found inside the vehicle.
The incident happened on Highway 10 on Friday night.
A vehicle somehow got wedged under the tanker truck, causing a fire that lasted approximately two hours.
The Sûreté du Québec has confirmed that the family was from Montreal and that the people inside the vehicle were two parents and two children.
Their ages are not known. The driver of the tanker truck was not seriously injured.
Investigators are trying to put together the sequence of events that led to the crash.
Sgt. Audrey-Anne Bilodeau of the SQ said there is a lot of construction going on in the area where the crash happened, but she could not confirm whether it was a factor in the crash.