It was the third time in a month that a passenger tried to commandeer one of the company's buses.
Charles George, of Phoenix, faces 37 counts of aggravated assault for the incident on a Florida-bound bus outside Phoenix early Sunday.
"We believe there was some mental instability we were dealing with," said Steve Volden, spokesman for the Arizona Department of Public Safety. "He didn't make any overt statements about wanting to hijack the bus or doing anything in the name of religion. It appears he was acting independently."
George, who was not armed, was treated for facial cuts at Casa Grande Regional Hospital and taken into custody. No other vehicles were involved.
Authorities said George apparently became angry at the driver after he was told to extinguish his cigarette.
George, who is about 40 years old, lit up a cigarette as the bus was about 50 miles south of Phoenix. He became upset when two off-duty bus drivers riding in the vehicle told him that he couldn't smoke, Volden said.
He went to the front of the bus and banged on the door of the vehicle. Unable to open the door, the man grabbed the steering wheel and tried to take control of the bus, Volden said.
The bus went off the pavement. The driver tried to steer it back onto the highway but the vehicle rolled over onto its side, Volden said.
The driver, whose identity was not immediately available, was hospitalized in stable condition. One of the injured passengers was listed in critical condition.
Five other passengers were in fair to stable condition, authorities said. Six passengers were treated and released and five were not injured. Conditions were not available Sunday for the other passengers.
The bus was en route from Los Angeles to Miami.
On Oct. 3, a Croatian man slashed the neck of a Greyhound bus driver in Tennessee, causing a crash that killed seven passengers. The incident prompted Greyhound to shut down all bus service for a few hours.
Two weeks later, passengers on a Greyhound bus were credited with averting disaster in Utah after they helped thwart an alleged hijacker who tried to overpower the driver and threatened to flip the vehicle. No one was injured.
Greyhound spokeswoman Jamille Bradfield said the bus company didn't suspend bus service after Sunday's crash because authorities believed it was an isolated incident.
By Ananda Shorey © MMI The Associated Press. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed