Story highlights

The bus driver and a passenger are critically injured

33 are injured in all

CNN —  

Thirty-three people were injured – two critically – in a bus accident Thursday morning near Gibbon, Nebraska, the American Bus Association reported.

The driver of the bus was among those critically injured.

Details of the accident were unclear, but it appeared that the bus either struck or was struck by an 18-wheeler, association spokesman Dan Ronan told CNN.

The incident happened on Interstate 80.

The Burlington Trailways bus was heading from Omaha, Nebraska, to Denver, Colorado.

CNN’s Tom Laabs contributed to this report.