Six people were injured in a shooting on a Greyhound bus traveling from Los Angeles to the Bay Area early Monday morning, officials said.

An unidentified man was taken into custody, according to California Highway Patrol communications supervisor Steve Loftus. Investigators have not determined a motive.

Police began getting calls from passengers on the bus, traveling on Interstate 5, at about 1:30 a.m. local time, Loftus said.

The bus had left Los Angeles about an hour earlier and following the shooting, the bus driver pulled off at the nearest exit, in Grapevine, south of Bakersfield.

About 40 people were on the bus, headed for the San Francisco-Oakland area, Loftus said. The six victims suffered injuries ranging from moderate to critical. Some were airlifted to the hospital.

This is a developing story, check back for updates.