A blinding snow squall led to a fiery pileup on a Pennsylvania interstate on Monday morning that involved at least 50 vehicles, including several tractor-trailers, the authorities said.
The chain reaction happened around 10:36 a.m. on Interstate 81 in Schuylkill County about 50 miles northeast of Harrisburg, Pa., where an early spring burst of wintry weather overwhelmed drivers in the northbound lanes.
About 20 people were taken to hospitals, John Blickley, a spokesman for the Schuylkill County Office of Emergency Management, said on Monday. He did not know of any fatalities and did not have information about the severity of the injuries.
“The road conditions when the squall came through contributed to the accident,” Mr. Blickley said.
The Pennsylvania Department of Transportation referred questions about the crash to the Pennsylvania State Police, which wrote on Twitter on Monday afternoon that 50 to 60 vehicles were involved in the pileup and that a fire continued to burn at the scene. It did not immediately provide details, including information about fatalities. The Associated Press reported at least three people were killed.
The pileup snarled traffic for several miles on the highway, making it difficult for emergency responders to reach the wreckage, which the authorities said extended for about a mile. The threat of additional snow squalls further complicated those efforts, prompting the authorities to shut down the highway for several hours. The southbound lanes of the highway reopened on Monday afternoon.
One driver who was involved in the pileup captured the chain reaction on video as it happened, and the diminished visibility that motorists encountered. The video, which drew widespread attention on social media, showed a convoy of tractor-trailers plowing into one other and skidding on the highway.
In the video, the driver of a sedan narrowly avoided being hit by another car after hitting a highway sign on the shoulder. One person could be heard yelling “go, go, go” as the man recording the footage urged other drivers to “watch out.”
Some drivers who had gotten out of their cars ran toward the woods as more cars and trucks slammed into the idled vehicles on the highway.
The man who captured the chaotic sequence expressed his disbelief as an S.U.V. plowed into his Dodge Charger.
“My car is gone,” he yelled.
It was the second time in just over a month that a snow squall was blamed for a major pileup on Interstate 81 in Schuylkill County. On Feb. 19, five people were injured in a pileup that involved about 50 vehicles near McAdoo, Pa., about 25 miles northeast of where the pileup on Monday happened, according to local media outlets. None of those injuries were life-threatening.