KNIGHTS FERRY, Calif. (AP) _ Speeding may have caused a tour bus with Japanese tourists to run off the highway and plunge into a ravine, injuring 27 of the 30 people on board.

Witnesses said the bus was traveling at least 70 mph, but by law is restricted to 55 mph, Sgt. Mike Dust said Thursday.

The bus went off the right side of the highway, down an embankment and 70 feet into the ravine.

All but one person, a 49-year-old woman who fractured her neck, have been released from the hospital.

The bus was on its way back to San Francisco from Yosemite National Park when the accident happened early Wednesday evening on the westbound lane of Highway 120.