Pittsburgh: The front of a city bus was left up in the air after a sinkhole opened under it during peak hour in downtown Pittsburgh in the US.

The Port Authority of Allegheny County said the only passenger on the bus was treated for a minor injury on Monday morning, local time.

The agency tweeted that the bus was at a red light when the street gave way and the rear half plunged into the hole.

A photo shows the front of the bus pitched into the air and the front wheels of a car that was behind it dangling over the sinkhole's edge.