Nobody at the wheel in Pa. school bus, truck crash

(CBS/AP) BEAVER FALLS, Pa. - This is a story about a crash involving a school bus and a truck that has a (relatively) happy ending.

That's because there was no driver in either vehicle, and no passengers, for that matter, at the time the collision occurred in northwest Pennsylvania.

Police in Patterson Township tell the Beaver County Times the incident happened just before 10 a.m. Tuesday when the parked bus began to roll down a hill. Police aren't sure why that happened, since the parking brake was engaged in the driverless bus.

The bus rear-ended a parked truck, which also began rolling down the hill alongside the bus, until the truck flipped onto its side. The bus continued on, shearing off one utility pole and hitting another before rolling to a stop a few feet from the porch of a home.

More good news.

Police don't plan to cite the drivers of either vehicle.