Five people were killed and dozens more injured in a deadly pileup involving a coach bus, a Mercedes, and three tractor-trailers on the Pennsylvania Turnpike early Sunday.

The Westmoreland County’s Office of the Coroner identified the five fatalities Sunday including the bus driver, Shuang Qing Feng, 58, of Flushing. Bus passengers Eileen Zelis Aria, 35, of the Bronx and Jaremy Vazquez, 9, of Brooklyn also died in the crash. Dennis L. Kehler, 48, of Lebanon, Pennsylvania and Daniel J. Kepner, 53, of Lewistown, Pennsylvania were UPS employees who also died in the collision.

The pileup happened about 35 miles southeast of Pittsburgh near Mount Pleasant around 3:40 a.m. Sunday, according to Pennsylvania State Police.

A passenger bus belonging to Z&D Tours of Rockaway, New Jersey and filled with tourists was bound for Cincinnati when Feng apparently lost control, striking the center barrier, veering right across the turnpike and leading to a “chain-reaction type crash,” according to the Pennsylvania State Police.

"As they were traveling, that bus was headed on a downhill grade and the bus was unable to negotiate a corner," Trooper Stephen Limani said at a press conference.

On Monday, Pennsylvania State Police released more details of the collision after Feng lost control. According to the preliminary investigation, the bus rolled over, slid back on the roadway and struck the center barrier again, while Feng was ejected from the bus. A FedEx truck driver struck the bus lying on its side, followed by a UPS tractor-trailer occupied by Kehler and Kepner. The driver of a Mercedes then hit the UPS tractor-trailer, followed by a second UPS tractor-trailer that pinned the Mercedes between the two trucks. Miraculously, the occupants of the Mercedes and the second UPS truck were not injured.

Limani said the weather may have been a factor, with fog, intermittent light snow and temperatures below freezing.

The New York Times reported that 18 people were taken to the University of Pittsburgh Medical Center Somerset where they were treated and released. Another 31 people were taken to Excela Frick Hospital in Mount Pleasant where 27 of them were treated and released.

Two people had critical injuries, Limani said, and added that police were still trying to identify passengers.

A bus passenger told ABC News that the driver was going about 70 mph and passed a slower FedEx truck that subsequently struck the bus.

"He swerved right, swerved left, clipped the median, and then swerved back into the grass area," bus passenger Lamar Brady of Cincinnati said. "Then we started tumbling maybe about two or three times. When we started tumbling, it was about two to three seconds where it was just like zero-G kind of because everything was just spinning in the air. And then we smacked on the side here. That's when everyone started like screaming and stuff."

Chen Dan Yu, owner of Z&D Tours, said 56 passengers were aboard the bus and departed from Canal Street in Manhattan, headed to multiple destinations in Ohio, according to the New York Times. The bus was labeled Ohio Coach, which Yu said was a company that handled ticket sales.

Z&D Tours has 15 drivers and has had no accidents or any safety violations in the last two years, according to the US Department of Transportation Records. The bus was about 15 years old, according to the police.

Limani of the Pennsylvania State Police said many of the passengers were foreign tourists who spoke mainly Japanese and Spanish. “The majority of those people are people from different countries and the majority of the people don’t have English as part of their language,” he said.

The National Transportation Safety Board said it will investigate the crash, which happened eight years after federal regulators cracked down on unsafe discount buses that depart from Chinatown.