At least three people were killed on a Pennsylvania highway Monday after a fiery collision involving more than 50 vehicles during a snow squall, authorities said.

Schuylkill County coroner Dr. David J. Moylan warned Monday afternoon that the death toll “could run higher” because the search of the scene hadn’t yet been completed because of burning vehicles.

The fiery crash occurred on Interstate 81 at about 10:30 a.m. near Minersville, about 100 miles northwest of Philadelphia, John Blickley of the county’s emergency management office, told USA TODAY. At least 20 people were sent to hospitals with injuries, he said. 

Footage uploaded to social media showed an out-of-control tractor-trailer smash into a large dump truck, turning it nearly 180 degrees. Another large truck spewed black smoke and orange flames into the air and an SUV struck a passenger car sending the sedan spinning, narrowly missing its driver who stood on the shoulder of the highway shrouded in snow and fog.

The collision closed all lanes of I-81 north in Schuylkill County and highway message boards were redirecting traffic, said Ronald Young, spokesperson for the Pennsylvania Department of Transportation. 

Pennsylvania State Police are investigating the crash and numerous local EMS, fire and police agencies are responding to the scene, police Lt. Adam Reed said. A number or tankers were on location to replenish water because there was no water source from hydrants.

WHAT IS A SNOW SQUALL? The weather phenomenon caused a whiteout in New York and Pennsylvania

A multi-vehicle crash on Monday during a snow squall has closed a portion of Interstate 81 in Pennsylvania.

Snowy conditions were making it difficult for emergency services to reach the scene, Blickley said.

Some people were trapped in their cars, Blickley said. Three tractor trailers were on fire and at least two other small fires were reported, he said.

Video shared on social media shows several tractor-trailers and other vehicles crashing into other stopped vehicles and onlookers watching black smoke and flames rising from what appeared to be a tanker truck. In one video, people off camera can be heard yelling as multiple vehicles are seen colliding in less than a minute.