A stretch of Highway 401 in Oshawa has been reopened after a collision sparked a massive tractor-trailer fire early Monday morning.

Flames and dark, billowing smoke could be seen from kilometres away around 4 a.m. as firefighters tried to get the blaze under control.

At least one other vehicle was involved in the collision with the tractor-trailer, but there were no reports of any major injuries.

Westbound lanes remained closed between Ritson and Harmony roads for about seven hours as Ontario Provincial Police investigated.