Investigators are continuing to look into the cause of a multi-vehicle crash that resulted in the deaths of four people, including one child, on Highway 400 on Friday night. The highway was closed for around 18 hours while officers were on the scene.

The incident happened in the southbound lanes of the highway near Sheppard Avenue at around 9:45 p.m.

Ontario Provincial Police say that there were 12 vehicles involved in the accident, including three transport trucks that sustained significant damage.

OPP Sgt. Kerry Schmidt told CP24 on Saturday least four were dead and they were still working to confirm the exact number. Police said one of the four victims was a child.

Schmidt said the highway had to be repaved because of the extensive damage. Around 3:30 p.m., the OPP said all southbound lanes on the highway at Finch Avenue were reopened.

“There is some incredible, incredible damage,” Schmidt said on Friday. “It’s unbelievable really. There are things I don’t think I have ever seen before.”

Witness Jeff Fisher told CTV Toronto that all he saw was “big burling smoke” and then “flames shooting up in the air over the sign.”

Another witness said, “I saw two cars upside down. I saw a minivan on its back.”

There have been no charges laid yet and the OPP collision reconstruction is investigating to figure out how the collision occurred. They said they believed road conditions were good.

Cars that were stuck in traffic near the accident eventually cut through the fencing on the shoulder to get out.

A man told CTV Toronto that he was driving in the area just before the crash, but decided not to take the highway.

“Last night, we decided to relax and you know, a 10-minute difference and I could have been here,” he said.

Fire crews worked to clean off the highway, but they said the damage was so severe two lanes had to be repaved.