Five people were killed and at least 60 were injured on the Pennsylvania Turnpike early Sunday morning, when a tour bus lost control on a hill and rolled over, setting off a chain reaction that involved three tractor-trailers and a passenger car.

The injured victims, ranging from 7 to 67 years old, are all expected to survive, though two patients remain in critical condition, authorities and hospital officials said Sunday afternoon. The crash, which happened at 3:40 a.m. on a mountainous stretch of the highway about 30 miles (50 kilometers) east of Pittsburgh, shut down the highway in both directions.

The tour bus, operated by a New Jersey-based company called Z & D Tour, was traveling from Rockaway, New Jersey, to Cincinnati, Ohio, Pennsylvania State Police spokesman Stephen Limani said at a press conference Sunday. He said the bus was traveling downhill on a curve, careened up an embankment and rolled over. Two tractor-trailers then struck the bus. A third tractor-trailer then crashed into those trucks. A passenger car was also involved in the pile-up. Photos from the scene show a mangled collision of multiple vehicles including a smashed FedEx truck that left packages sprawled along the highway.

“It was kind of a chain-reaction crash," Limani said.

FedEx did not provide any other details besides that they are cooperating with authorities. A message seeking comment was left Sunday with the bus company.

Limani would not identify those killed or say which vehicles they were traveling in because families have not yet been notified.

“I haven't personally witnessed a crash of this magnitude in 20 years," Pennsylvania Turnpike spokesman Carl DeFebo told WTAE, calling it the worst accident in his decades-long tenure with the turnpike. “It's horrible."

Excela Frick Hospital in Mt. Pleasant treated 25 victims, nine of them children, hospital spokeswoman Robin Jennings said.

Hospitals brought in teams of social workers and psychologists to deal with the mental trauma, said Mark Rubino, president of Forbes Hospital, which treated 11 victims.

“The people coming in were not only physically injured but they were traumatized from a mental standpoint as well," he said. Most were covered in diesel fuel when they arrived. The hospital treated fractured bones, brain bleeds, contusions, abrasions. Some required spinal surgery.

The victims included students and people returning from visiting family in New York City. Many traveling on the bus were from outside the United States, Limani said, some of whom do not speak English and who lost their luggage and passports in the wreckage. Limani said the Red Cross was working with those patients to find housing and resources. Authorities brought in translators to assist with the investigation and medical treatment, and also to help the victims reconnect with their loved ones.

The Tribune-Review reported Leticia Moreta arrived at a hospital about 11:30 a.m. to pick up her children - Jorge Moreta, 24, and Melanie Moreta, 16 - who were on the bus.

She said her children, returning from visiting their father in New York, were in stable condition.

“I was devastated,” she said.

Exactly what caused the crash remains unknown, and Limani said it could take weeks or months to determine. The National Transportation Safety Board announced Sunday that it dispatched a team of more than a dozen to investigate.

Officials said it was too early to determine if weather was a factor in the crash. The National Weather Service forecast for Westmoreland County early Sunday listed light unknown precipitation and an air temperature just below freezing.

Angela Maynard, a tractor-trailer driver from Kentucky, said the roads were wet from snow but not especially icy. Maynard was traveling eastbound on the turnpike when she came upon the crash site and called 911.

“It was horrible,” she told The Tribune-Review. She saw lots of smoke but no fire. She and her co-driver found one person trapped in their truck and another lying on the ground.

“I tried to keep him occupied, keep talking, until medical help arrived," Maynard said. “He was in bad shape. He was floating in and out of consciousness.”

More than 90 miles of the Pennsylvania Turnpike, from Stanton to Breezewood, remained closed in both directions indefinitely. Local fire and emergency medical crews are on scene, along with a hazardous material company cleaning up fuel and other materials. A towing company is getting ready to begin separating the vehicles and getting them cleared.

“It's a very extensive crash so a lot of work has to be done to get the roadway reconditioned and ready to handle traffic again," said Craig Shuey, the turnpike's chief operating officer.

The crash left families terrified and scrambling.

“I was crying,” said Omeil Ellis, whose two brothers were on the bus. “I was like crazy crying. I’m still hurt.”

Ellis, from Irvington, New Jersey told The Tribune-Review, that his brothers were traveling to Ohio for work. He was planning to meet them a few days later. But both of his brothers, one of them 39 years old and one 17, are now in hospitals.

“I’m just weak right now,” he said.