NEEDLES, Calif. (CBS/AP) — A tour bus caught fire in the Southern California desert, prompting the driver and 52 passengers to evacuate before the bus became engulfed in flames.

San Bernardino County Fire officials say the bus was traveling to Ventura Sunday around 1 p.m.  when it caught fire on Interstate 40.

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The bus driver said he heard what sound liked a rear tire exploding and pulled over. When he got out, he saw the back of the bus on fire.

Fire spokesman Dean Dickover said the passengers safely evacuated. One passenger had a respiratory emergency, and three others suffered heat-related problems.

Dickover said the passengers were stranded in 90-degree heat until emergency crews arrived.

The bus operated by San Luis Obispo-based Silverado Stages is a total loss.

KCAL9’s Jasmine Viel said the 52 passengers are all employees of Ventura Community Memorial Hospital.

The group was traveling back to Ventura from a business trip to Laughlin, Nevada.

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Officials gave the bus driver credit for getting everyone off the bus quickly and safely.

Passengers scrambled to retrieve their luggage.

Authorities told Viel the cause of the fire is still under investigation.

Viel spoke to one co-worker who didn’t make the trip.

“I was just shocked,” said Amy Sulit, “we heard the bus burned down and we got all worried. I’m just here to make sure everybody is okay.”

Sulit said she was on the very same trip last year when that bus got lost going to Nevada and ended up in Utah.

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