Stretch of Highway 401 closed in Pickering, Ont., after fiery crash leaves 2 dead

A fiery crash Tuesday night claimed the lives of two people on Highway 401 east of Toronto in Pickering, Ont., and when that key stretch will reopen to traffic is yet to be determined, police say.

The collision involving two transport trucks and a passenger vehicle caused an explosion and fire that consumed all three vehicles on the highway near Brock Road at around 10:30 p.m., according to Sgt. Kerry Schmidt, spokesperson for the Ontario's Provincial Police highway safety division.

Schmidt said one of the transport trucks was carrying "highly flammable fuel" when the driver lost control. The truck struck the centre wall of an overpass and rolled over onto the other side of the highway, which ruptured its tanks and created a "massive fireball," he said.

Another transport truck was travelling westbound when it struck the trailers and was then consumed by the fire, he said.

"It's a highly flammable derivative of a diesel camping fuel oil, it's a dangerous good [that's] highly flammable and we saw the outcome and the results of that last night," Schmidt told reporters at the scene Wednesday.

"[Gas] from the fuel tanker truck was leaking and burning, it was actually going down into the catch basins, which also caused explosions in the sewer system."

Both transport truck drivers were found without vital signs and pronounced dead at the scene, Schmidt said.

The driver and a passenger in the third vehicle were not injured and were able to escape the explosion and fire, he said.

The OPP later released video showing that manhole covers had been blown off the ground from the force of explosive gases in the sewers.

Explosive power as a result of the fatal collision <a href="https://twitter.com/hashtag/Hwy401?src=hash&amp;ref_src=twsrc%5Etfw">#Hwy401</a>/Brock Rd Pickering. <a href="https://twitter.com/hashtag/TorontoOPP?src=hash&amp;ref_src=twsrc%5Etfw">#TorontoOPP</a> <a href="https://t.co/eqrpgMRzCX">pic.twitter.com/eqrpgMRzCX</a>

The fire caused damage to the Brock Road overpass, Schmidt said, though the severity isn't yet clear.

The OPP said Ministry of Transportation engineers are inspecting the highway, including the overpass, to determine if the crash compromised its structural integrity.

In a statement on Wednesday night, the ministry said it is working "to explore all available options for an emergency detour to keep people and goods moving on this critical highway."

The ministry said it is still assessing damages, with one eastbound collector lane being used for a detour.

"Once the extent of the damage is known, a schedule for reopening will be released," the ministry said.

WATCH | Driver says he panicked when he saw a 'massive fireball':

Hundreds of vehicles were stuck in traffic Tuesday night as a result of the collision, said Schmidt.

On Wednesday, the 401 remained closed westbound from Westney Road in Ajax to Liverpool Road in Pickering. Traffic is getting through eastbound but with heavy delays, as drivers are being directed off the highway at the Brock Road off-ramp and back onto the highway at the Brock Road on-ramp, he said.

Anyone who travels through the region should plan an alternate route, Schmidt advised.

On Wednesday afternoon, the Regional Municipality of Durham said residents should expect increased traffic congestion in the area.

"Allow for extra travel time on Durham roads," the region said in a news release.

Delays and some cancellations are expected to continue throughout the day, it added.

Schmidt described the scene of the crash as "very horrific" and "tragic," with witnesses reporting that they saw the sky light up with fire at night.

Dylan Mohammed was driving to Vaughan when he came up on the fiery crash.

"Just cruising on the highway and all of a sudden, I saw this explosion, I didn't even know what to do, just a massive fireball," Mohammed told CBC Toronto.

WATCH | Multi-vehicle crash sparks massive fireball, explosions:

​"I panicked and I had to literally swerve​ right and stop ... in a matter of five seconds, I would've been involved in that."

The explosions were loud enough for residents living near the highway to hear them from inside their homes.

"We were just watching TV and all of a sudden, we heard a major explosion and bright lights coming into our townhouse," said Norm Belley.

"It was very scary. We jumped out of our seats and we ran out to look quickly to see."

Stephen Laskowski, president of the Ontario Trucking Association, says the entire trucking community extends condolences to the families of the drivers who lost their lives in the crash.

"The Ontario Trucking Association would ask all members to take a moment of silence or [find] another suitable way to remember these drivers," Laskowski said.

Police initially advised residents living in the area to keep their windows and doors closed as a precaution due to smoke from the fire, saying they were unsure if the liquid from the trucks was toxic. On Wednesday, Schmidt said the fumes were found to be not toxic.

Police say they are looking to speak to the occupants of a red Chevy Volt who were involved in the collision on the 401.

Anyone who may have been in the area at the time of the collision is being asked to contact investigators.

With files from The Canadian Press