Story highlights The bus left the casino a little more than an hour before the crash

Twelve of the 13 fatal victims are identified

(CNN) There was "no appearance of braking" when a tour bus slammed into the rear of a tractor trailer on Sunday, near Palm Springs, California, killing the driver and 12 passengers and injuring dozens, a state police official said Monday.

"There were no skid marks from the bus at the time of the collision," California Highway Patrol Border Division Chief Jim Abele told reporters. "The only skid marks were directly related to the big rig as it got pushed forward."

Police said the 1996 MCI bus, operated by USA Holiday, was returning to Los Angeles from the Red Earth Casino near the Salton Sea when it crashed into the tractor trailer around 5:17 a.m. PDT on Sunday. The crash happened a little more than an hour after the bus left the casino, according to Abele.

The chief said he was told by an officer at the casino that the bus arrived there between 11 and 11:30 p.m. on Saturday and left around 4 a.m. on Sunday.

Authorities on Monday identified 12 of the 13 people who were killed including the driver, Teodulo Elias Vides, 59, of Los Angeles. The Riverside County Coroner's Bureau confirmed that 10 of those killed were women and three were men.

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