A Greyhound bus struck a tractor-trailer early Wednesday on I-80 in central Pennsylvania, killing a woman, critically injuring four other people including the bus driver and sending dozens to the hospital, authorities said.

Trooper Matthew Burrows of the state police barracks in Milton said the bus was extensively damaged when it hit the rear end of a flatbed trailer that was hauling garbage about 1:30 a.m. in the westbound lanes of I-80 in Union County’s White Deer Township.

Greyhound spokeswoman Alexandra Pedrini said 38 of the 49 passengers transported to five hospitals were treated and released by late Wednesday afternoon, and then placed on replacement buses to their final destination. She said the bus driver, Sabrina Anderson, 42, was one of the four people in critical condition.

The bus was heading from New York City to Cleveland. Anderson has been with the company for more than 12 years, Pedrini said.

The driver of the tractor-trailer, Akos Gubica, 36, of New Jersey, said his rig was struck from behind by the bus.

“Just a big jolt from behind me, I pulled over to the shoulder, got out of my truck there just a lot of screaming from the people on the bus, people climbing out of the windows,” Gubica, who was uninjured, told Scranton, Pa.’s, WNEP news.

He said he drives the route about every three days.

Pedrini declined to comment on the circumstances of the crash, saying the company was cooperating with authorities in their investigation and was conducting an internal probe.

The section of I-80 where the crash occurred was shut down for about 15 hours.

It was the second serious accident involving a Greyhound bus in less than a month. On Sept. 14, one of the company’s buses veered off I-75 near Monroe, Ohio, and landed on its side in a cornfield. Dozens of the 51 passengers, as well as the driver, were injured.

State troopers confirmed to the Dayton Daily News that driver Dwayne Garrett, 64, had choked on his coffee just before the crash and passed out.