NTSB says deadly 2016 Palm Springs bus crash caused by fatigued drivers

PALM SPRINGS, Calif. (KABC) -- The National Transportation Safety Board is blaming sleepy drivers for causing a deadly bus crash in Palm Springs in October of 2016.

A tour bus driver and 12 passengers were killed when the bus slammed into the back of a big rig stopped in a lane of westbound I-10.

MORE: 13 dead, 31 injured after tour bus crashes into truck near Palm Springs

The bus was returning to Los Angeles after a trip to Red Earth Casino.

MORE: Truck driver arrested for causing 2016 bus crash that killed 13 near Palm Springs

The big rig's driver, 51-year old Bruce Guilford, was charged with vehicular manslaughter and reckless driving.

He was arrested in Georgia two weeks ago and is awaiting extradition back to California to face charges.