At least 13 people are dead and several more were rushed to local hospitals after a tour bus collided with a semi-truck early Sunday morning in California, Fox News confirmed.

The crash occurred around 5 a.m. in the westbound lanes of the 10 Freeway at Indian Canyon in the Desert Hot Springs area. The big rig driver was unhurt, according to The Desert Sun.

"At this time, we know that there are multiple fatalities. We can't give an amount because that number is going to change," California Highway Patrol Officer Stephanie Hamilton said "There are approximately 31 passengers on the bus that were transported [to local hospitals] with minor to serious injuries."

The tour bus was identified as a USA Holiday bus. The Los Angeles-based company typically ferries people from LA to Southern California casinos, The Desert Sun reported.

Authorities shut down the freeway in the aftermath of the incident. Details on a possible cause of the crash were unclear.

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

"The intrusion into the bus compartment is significant," Hamilton said.

Firefighters were using ladders placed near the bus' windows to pull out victims. It took nearly two hours to separate the vehicles, Fox News reported.

The Palm Springs hospital treated 14 patients, five in critical condition, three in serious condition and six with minor injuries. Palm Springs houses the valley's only trauma center, The Desert Sun Reported. All patients were adults.

Desert Regional director of marketing Rich Ramhoff said it was the most victims he'd seen from a single incident.

Eleven people with minor injuries were sent to Eisenhower Medical Center in Rancho Mirage, spokesperson Lee Rice said. JFK Medical Center received five patients, all with minor injuries, chief development officer Linda Evans said.

The Associated Press contributed to this report.