DOLAN SPRINGS, Ariz. (AP) — A Las Vegas-based tour bus heading to the Grand Canyon rolled over in northwestern Arizona on Friday, killing one person and critically injuring two others, authorities said.

The cause of the wreck around noon Friday was not yet known, said Anita Mortensen, a spokeswoman for the Mohave County Sheriff’s Office. It wasn't clear if any other vehicle was involved. A photo from the sheriff's office showed the bus on its side on a curving road, with no snow or rain in the remote area.

There were 48 people on the bus, including the driver. It was heading to Grand Canyon West, outside the boundaries of the national park, which sits on the Hualapai reservation. It’s best known for the Skywalk, a glass bridge that juts out 70 feet (21 meters) from the canyon walls and gives visitors a view of the Colorado River 4,000 feet (1,219 meters) below.

Of the 42 people on the bus brought to the hospital, two were critically injured, seven had less serious injuries and 33 suffered minor injuries, Mortensen said.

John MacDonald, a spokesman for the Hualapai tribe, did not immediately have any further information. National Transportation Safety Board spokesman Keith Holloway said he didn’t immediately have more information about the crash or about NTSB involvement.

A spokeswoman for Grand Canyon West, did not immediately return messages seeking more information.

In 2009, a tour bus carrying Chinese nationals overturned on U.S. 93 near the Hoover Dam, killing several people and injuring others. The group was returning from a trip to Grand Canyon.