Mexican authorities say 11 people have died from a bus plunging into a ravine while headed to the Pacific resort of Mazatlan.

Durango state government Secretary Jaime Fernandez Saracho says the bus fell about 150 feet from a mountainous road known as the "Devil's Backbone." Twenty-two other passengers have injuries.

Fernandez says Friday's early morning accident could have been caused by fog and the driver not knowing the road.

He says the victims were mostly senior citizens, although one was a 13-year-old boy.

The rescue took hours in the rough terrain. Many of the injured were flown by helicopter to Durango and Mazatlan hospitals.

The accident came four weeks to the day after a bus fell off a cliff in Nayarit state, killing 24 people.