Provincial police say a westbound pickup truck collided with an eastbound tractor-trailer on Highway 17 on Saturday night in the community of Upsala, outside Thunder Bay.
Sgt. Shelley Garr says the driver of the tractor-trailer died in the crash along with all four men in the pickup truck.
Garr offered few details, saying only their names could not be released because all their family members have yet to be notified.
Investigators say two other vehicles were also damaged in the crash but that there were no injuries.
The highway was closed for 12 hours and police remained on the scene Sunday as they try to figure out what caused the crash.