Bales of hay fell off a truck into a bus Friday, causing a collision that injured 28 people heading for a polka convention in New York, police said.

Five of the injured were hospitalized and the others were treated at hospitals and released, state trooper Mike Tenuto said.The accident in Upper Macungie Township occurred when the truck swerved, causing bales to drop off the back, Tenuto said. They smashed through the windshield of the bus, he said.