A Greyhound bus with 40 passengers aboard flipped onto its side on Interstate 65 in northwestern Indiana. Several people were hurt in the incident, but there weren’t reported severe injuries, authorities said.

All the passengers were taken to the nearest hospitals to undergo some standard health tests. Nobody suffered life-threatening injuries, state police Lt. Larry Keiser said.

The bus traveling from Chicago to Indianapolis crashed at about 10 a.m. Central time nearly 15 miles south of Gary. The vehicle landed on its passenger side and with its wheels against the concrete barriers in the motorway’s median.

The cause of the accident is still unknown, but the road was clear and dry when the bus crashed. Police arrived at the scene as soon as possible and shut down all lanes of southbound I-65, with northbound lanes remaining open. The expressway reopened to traffic just before 2 p.m.

According to Greyhound spokesman Kim, there were 41 people on the including the driver. Six passengers were taken by ambulance for medical care, while other were taken with a school bus and taken to St. Mary Medical Center in Hobart.

A Greyhound relief bus picked up the passengers who were not injured.

According to some passengers, the driver may have fallen asleep, although he had a very good driving record in his 18 years with Greyhound, Plaskett said.