IROQUOIS, Ont. -- A young Quebec woman, her grandmother and her infant daughter were killed early Monday in a fiery crash involving a van and a tractor-trailer in eastern Ontario.

Ontario Provincial Police said the crash sparked a fire and sent both vehicles into a ditch on the south side of Highway 401, about 60 kilometres west of Cornwall.

Twenty-two-year-old Elissa Reid, 78-year-old Sheila McGlashen and two-month-old Moriah Gloria Warren, all from Chateauguay, Que., were pronounced dead at the scene.

Three other people in the van sustained injuries considered serious but not life-threatening and were taken to hospital.

The truck driver, 44-year-old Sergey Lucin, of Toronto, was treated for minor injuries and released.

All lanes of the 401 were temporarily closed for the investigation but police reopened the westbound lanes by mid-morning.

One of the eastbound lanes remained closed in the early afternoon as emergency crews removed the tractor-trailer from the ditch.

Police have not released any information about what may have caused the crash.