Four people have died in a fiery, multiple vehicle crash on a stretch of Highway 401 in eastern Ontario that happened overnight on Thursday.

Four tractor-trailers, a commercial truck and two passenger vehicles were involved in the pileup near Kingston, Ont. just before 1:30 a.m. on Thursday.

Ontario Provincial Police say they believe the four people killed were inside a passenger vehicle that caught fire. Investigators did not provide information on the ages, genders or relationships of the deceased. OPP Const. Roop Sandhu told CTV News at the crash site that it is a “very terrible scene to come into, especially with the amount of fire that we’ve seen.”

He added, “The vehicle is almost unrecognizable.”

Two unidentified males were taken to hospital with serious injuries.

“One male had to be extricated from the one commercial vehicle and I was advised that his injuries were serious, unknown if they were life-threatening,” said OPP Sgt. Angie Atkinson.

One of the vehicles involved in the pileup was a Garda armoured truck, which lay on its side in a ditch after the crash.

Garda employees arrived at the crash scene around 10 a.m., to try to determine how or when they’d be able to remove valuables from the armoured vehicle.

CTV Ottawa’s Annie Bergeron-Oliver reported that investigators are using a drone to capture images of the wreckage as they collect evidence and try to determine the cause.

The westbound lanes at the accident scene near Joyceville Road were closed as police investigated, but reopened Thursday evening.

With files from CTV Toronto and The Canadian Press