A Greyhound bus with 44 passengers onboard slid off the road, flipped over and hit a tree in Santa Maria, Calif., this week, killing two and injuring dozens of others.
The bus, which was heading from Los Angeles to San Francisco, veered off the road early Sunday morning, leading some to suspect that the driver fell asleep.
“We have reason to believe that driver fatigue may have played a significant factor here,” Lt. Dan Minor of the California Highway Patrol told the Los Angeles Times.
A 23-year-old pregnant woman and a 50-year-old man, who were both seated in the same row on the left side of the bus, died at the scene of the accident.
The other injuries ranged from minor to moderate, said police.
Authorities are investigating whether the driver had violated state and federal hours-of-service regulations.