More than 30 people were injured after a Greyhound bus overturned on an Ohio interstate early Saturday, authorities said. The bus was heading northbound on I-75 in Butler County, Ohio when it overturned shortly after 4 a.m., Butler County Emergency Operation Center officials said in a news release. The bus was carrying 52 people. Thirty-Four people were transported to area hospitals, including six people who were air lifted. The cause of the accident has not been determined.