Updated

A tour bus carrying high school students crossed a highway median and struck a car, killing the car's driver and injuring seven students on the bus, authorities said Thursday.

Investigators have not determined how the bus driver lost control around 10:40 p.m. Wednesday, said Highway Patrol Lt. Lawrence Roseboro. The bus was bringing home about 50 Dayton-area students from a trip to Washington.

Bus driver Loren R. Porter, 72, of Fairfield, told The Associated Press the accident started when a semitrailer merged in front of him on the highway. He would not elaborate.

Porter was cited for failure to maintain control, a misdemeanor, Roseboro said. Prosecutors will review the patrol's investigation to determine whether to file other charges, he said.

The bus left the westbound lanes of Interstate 70, drove through a guardrail in the median and crashed head-on into an eastbound car driven by Kerry Heider, 52, of Murrysville, Pa., police said.

Heider, the car's only occupant, was pronounced dead at the scene about 30 miles east of Columbus.

Seven students on the bus were treated at Licking Memorial Hospital in Newark and released, said their principal, Sister Katie Hoelscher of Alter High School in Kettering, 90 miles west of the accident site. One suffered a broken foot and one received stitches in the forehead, she said.

The students, their chaperones and Porter were taken home on another bus, Roseboro said.

The accident closed the eastbound lanes of I-70 for about seven hours, the patrol said.