By Jacques Billeaud and Felicia Fonseca | Associated Press

PHOENIX — 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, authorities said. After the crash, 44 people were sent to Kingman Regional Medical Center, including two flown by medical helicopter, spokeswoman Teri Williams said. All the others were treated for minor injuries, she said.

Mortensen said two people were critically injured.

The bus was heading to Grand Canyon West, about 2 1/2 hours from Las Vegas and outside the boundaries of the national park. The tourist destination sits on the Hualapai reservation and is best known for the Skywalk, a glass bridge that juts out 70 feet from the canyon walls and gives visitors a view of the Colorado River 4,000 feet below.

Before the pandemic, about 1 million people a year visited Grand Canyon West, mostly through tours booked out of Las Vegas. The Hualapai reservation includes 108 miles of the Grand Canyon’s western rim. In addition to the Skywalk, it has helicopter tours, horseback rides and a one-day whitewater rafting trip on the Colorado River.

The Hualapai reservation also has a road to the Colorado River where rafters who have permits through the national park can get on and off trips.

It’s also near where four Chinese nationals died in 2016 when their van collided with a Dallas Cowboys staff bus headed to a preseason promotional stop in Las Vegas.

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.

Federal investigators cited driver inattention as the probable cause of the crash. The bus driver was attempting to fix a problem with airflow through his door before the crash and became distracted, then veered off the road and overcorrected before crossing a median and overturning. Most of the passengers were ejected. The tour guide and six Chinese tourists were killed.

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

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

Fonseca reported from Flagstaff. Associated Press reporters Ken Ritter and Michelle L. Price in Las Vegas, Terry Tang in Phoenix and AP/Report for America Statehouse News Initiative corps member Sam Metz in Carson City, Nevada, contributed.