MARATHON, Ont. -- Police say three of the four people who died in a collision between a car and a pickup truck east of Thunder Bay, Ont., were from the same family.

The incident occurred around 10:25 p.m. Sunday (on Highway 627) outside the town of Marathon when the truck, driven by 36-year-old Greg Nabigon, collided with the sedan, killing him and three of the car's occupants.

Staff Sgt. Chris Whaly says the sedan was driven by 20-year-old Janet Leclair and was carrying two of Nabigon's relatives, 22-year-old Jordan Nabigon and 17-year-old Kody Nabigon.

Whaly says the family members were from Pic River First Nation.

He says a 42-year-old female passenger of the truck remains in a Thunder Bay hospital in serious condition.

Whaly says a 17-year-old boy not related to the Nabigon family who was riding in the sedan was treated for injuries in Marathon Hospital and released.

The investigation continues as officers work to establish the sequence of events leading up to the crash, Whaly said Tuesday.

The Marathon-area crash was the deadliest incident on the province's roads last long weekend.

Provincial police say four other people were killed in vehicle collisions.