NEW YORK (CBSNewYork/AP) — Two Italian citizens – one of them a pharmacist on the way to his honeymoon – and a bus driver from New York City were identified Thursday as the victims of a deadly eastern Pennsylvania highway crash involving a tour bus and a tractor-trailer.

The cause of the wreck remained a mystery late Thursday.

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Pennsylvania State Police on Thursday were investigating why the truck crossed a wide, grassy median and went into the path of a charter bus taking Italian tourists from New York City to Niagara Falls. The company that operated the truck refused to release details on the driver or his route or say how long he’d been on the road that day.

Police identified two victims Thursday: Marco Fornasetti and Rino Guerra, both passengers on the bus. The Italian news agency ANSA said Fornasetti, 29, was a newlywed from the northern city of Vicenza and his bride, a pharmacist like him, was among the injured. Police said Guerra, 69, was an Italian citizen.

The bus driver, Alfredo Telemaco, 54, of New York City, also died.

The crash occurred shortly after 10 a.m. Wednesday on Interstate 380 in Coolbaugh Township in the Pocono Mountain region — about 115 miles north of Philadelphia, according to Monroe County, Pennsylvania, emergency officials.

More than a dozen people were injured and taken to hospitals. Two people remained in critical condition Thursday.

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Owner Academy Bus said the bus had left New York at 7:30 a.m.

The mangled front end of the bus was upright on the highway but wedged into the side of the tractor-trailer, which was sheared in half. The cab of the truck came to rest on its side in the woods next to the road, one of its axles torn off.

It appeared from a wide swath of grass scraped away in the median that the tractor-trailer was southbound when it crossed over the divided highway and into the path of the northbound bus. State police said a second tractor-trailer was involved but they were still investigating what led to the accident.

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“It’s going to take a little bit of time to determine why the crash occurred,” Trooper David Peters said.

Monroe County, Pennsylvania coroner Robert Allen said the tractor-trailer driver didn’t appear to have been severely injured.

State police identified the driver as Franklin Dale Wyatt, 55, of Macomb, Oklahoma. Police said he was driving for Greatwide Dedicated Transport. Greatwide merged with Cardinal Logistics Management Corp., of Concord, North Carolina, two years ago.

Cardinal said “there are no words that can do justice to the sorrow we feel” after the “terrible accident.”

“We are praying for the families and friends of the passengers who lost their lives or were injured, and our hearts go out to everyone involved,” Cardinal said in a statement, adding it was cooperating fully with crash investigators.

A Cardinal spokeswoman said she had no other details and did not respond to questions about the driver.

An Associated Press review of Wyatt’s driving record turned up only two minor infractions: a 2012 speeding offense in Oklahoma and a 1997 incident in Oregon involving his tires.

Italian tour operator Viaggidea said 16 people were on the bus: 14 passengers, a tour guide and the driver. Viaggidea said it was “dismayed, shocked and deeply upset” by the crash and set up a crisis center in Milan.

Academy Bus said the driver had more than a decade of experience with the company.

After sightseeing in New York, the group was headed to Niagara Falls, then Toronto, Washington and Philadelphia, before returning to New York, according to an itinerary for the eight-day trip.

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