A passenger slashed the throat of a Greyhound bus driver Monday night as the bus headed down a California highway, causing it to careen out of control. Two people died and dozens were injured.

The bus, en route from Los Angeles to San Francisco, flipped on its side about 9 p.m. and slid into a cotton field about 500 feet off I-5 near Fresno. The bus reportedly was carrying as many as 60 passengers.

Officials said the attack was not related to terrorism. The suspect, identified as Arturo Tapia Martinez, is a transient from the Los Angeles area.

Twenty-seven people were taken to hospitals, according to published reports. Three, including the driver, were in serious condition.

About one year ago, on Oct. 3, 2001, a passenger on a Greyhound bus in Tennessee cut the driver's throat, causing a crash that killed seven. Two weeks later, passengers on another Greyhound bus in Utah were credited with averting disaster after they helped thwart an alleged hijacker.

Dallas, TX-based Greyhound has since hired a private company to screen some passengers with electric wands but has inspectors at only a portion of its terminals.