PITTSBURGH — A woman has died after her vehicle plunged 70 feet into the Ohio River from a railroad bridge in Pittsburgh, leaving authorities to investigate how and why she drove it there.

The Allegheny County medical examiner has yet to release the name of the woman whose body was found in the vehicle after she drove off the Norfolk Southern bridge about 2 p.m. Thursday. A spokesman says the vehicle didn’t belong to the railroad and wasn’t authorized to drive on the bridge.

Pittsburgh River Rescue Chief Raymond Everitt says the vehicle was found in water about 20 feet deep. A cat believed to have also been in the vehicle was found swimming nearby and rescued.

The bridge is normally used only by freight trains.