The California Highway Patrol says at least 10 passengers were killed when a tour bus and a semi-truck crashed on a highway in Southern California.

CHP Officer Stephanie Hamilton tells the Desert Sun newspaper in Palm Springs (http://desert.sn/2ekf1LI ) that crews were searching the bus for more victims after the wreck early Sunday on Interstate 10 in Desert Hot Springs, near the desert resort town.

The newspaper reports at least 21 victims have been taken to Palm Springs-area hospitals.

Photos show the front of the passenger bus pushed into the semi-truck's trailer.

Hamilton says "the intrusion into the bus compartment is significant."

Firefighters are using ladders into the bus' windows to pull out victims.

The CHP says all westbound lanes of the highway are closed and traffic is being diverted.

Information from the Associated Press and KESQ-TV was used in this report.