Transport authorities were investigating Monday how a bus idled for five hours at Port Authority terminal with its dead driver inside.

The NJ Transit bus from Meadowlands Station in East Rutherford, NJ, arrived Thursday at 10:30 a.m. Five hours later, the driver, Thomas Truex, was discovered slumped dead in a passenger seat, The Record reported Monday.

NJ Transit officials called the driver’s wife at 3 p.m., and she confirmed that he was missing. NJ Transit officials then called the Port Authority, and a supervisor found the body.

Truex’s death was not being treated as suspicious, although the cause of death was not known.