(CNN) A pileup involving three tractor-trailers, a tour bus and a passenger car killed five people Sunday and injured at least 60 others in western Pennsylvania, authorities said.

The crash happened around 3:34 a.m. on the Pennsylvania Turnpike in Mount Pleasant Township, southeast of Pittsburgh, the Westmoreland County Department of Public Safety said.

The bus, which was headed from New Jersey to Cincinnati, was traveling on a downhill grade when it failed to negotiate a corner, went up an embankment and rolled over, Pennsylvania State Police spokesman Stephen Limani told reporters.

The overturned bus was struck by two tractor-trailers, which in turn were hit by a third tractor-trailer, Limani said. A passenger vehicle was then involved in the crash, he said. A FedEx and UPS tractor trailer were involved in the pileup.

UPS said two drivers, Daniel Kepner, 53, and Dennis Kehler, 48, who were driving the tractor trailer were killed.

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