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PITTSBURGH (KDKA) — Pennsylvania State Police say the driver of a tractor-trailer that crashed and shut down traffic on Interstate 79 on Thursday died before his vehicle crashed.

The tractor-trailer overturned between the Interstate 279 split and the Mt. Nebo Road exit around 4:30 a.m., shutting down southbound I-79 traffic for hours.

State police say the driver — identified as 58-year-old Russell T. Brown, of Bensalem — was killed before the crash.

According to state police, he suffered an unknown medical emergency while driving and lost control of his tractor-trailer. The vehicle went off the right shoulder, traveled into a ditch, hit an embankment and then hit a fence.

When state police arrived on the scene, the inside of the cab was engulfed in flames. Authorities extinguished the fire and found Brown dead in the cab.