A Greyhound bus drove off an interstate highway in southwest Ohio early Saturday, struck a tree and a fence and flipped on its side before sliding to a stop in a cornfield, injuring 34 people.

None of the injuries was considered life-threatening, though several people were trapped and had to be extricated by firefighters and paramedics, the state highway patrol said in a statement.

The bus drove off the right side of northbound Interstate 75 about 25 miles north of Cincinnati at about 3:50 a.m., the highway patrol said.

Butler County Emergency Operations Center officials said 34 people were taken to hospitals, six by helicopters and 28 by ambulance. The injuries ranged from minor to severe, the officials said.

The bus, which left Cincinnati bound for Detroit, was carrying 51 passengers and the driver. Those passengers who were not injured were transported back to Cincinnati, but none of them were at the bus station later Saturday morning.

There was no immediate word on the cause of the crash, and officials said it remains under investigation.

A message left for Greyhound officials was not immediately returned.