The Port Authority of Allegheny County is investigating why a bus driver fell out of his seat, forcing a passenger to take the wheel and steer the transit vehicle to safety.
The incident happened about 9:45 a.m. Monday as the bus traveled on a ramp from Interstate 376 west out of the city onto busy Banksville Road.
Port Authority spokesman Jim Ritchie credited the quick-thinking passenger with steering the bus to safety.
The driver and two passengers were treated at Pittsburgh hospitals, while five other passengers weren't hurt.
Authorities haven't identified the driver or said what may have caused him to fall out of his seat leading to the passenger's actions.
The bus scraped a concrete jersey barrier, but the passenger was able to stop it after about 500 feet.