Highway 401 westbound lanes near Kingston, Ont., reopened just after 8 p.m. after an early-morning collision involving four tractor trailer transports.
Eastbound lanes were also closed until about 11 a.m. after the spectacular collision, which happened near Joyceville Road at about 2:45 a.m.
Two of the transports caught fire, and one truck was carrying peat moss.
"It's my understanding at this time that two drivers were treated on scene, and two drivers were transported to local hospital with undetermined injuries," said Kingston deputy fire chief Gary Bullock.
The incident created a massive traffic jam along the highway, as row upon row of transports lined up behind the scene.
Ontario Provincial Police had indicated the westbound lanes would need more time before they reopened as the fire required repairs to the road itself.
The Ministry of Environment was also at the scene investigating a fuel spill from one of the trucks.
Poor conditions on roads
Ottawa resident Sean Taylor drove by the crash scene on his way back to Ottawa from Grand Bend, Ont., and said one of the trailers had clearly caught fire.
"One of the trailers was right down to its metal rims sitting in the middle two lanes," he said.
He said poor road conditions because of snow and freezing rain made for a slow drive along the highway.
"I've seen more cars in the ditches than I think I've ever seen," said Taylor.