(Photo: AP)

A bus carrying Chinese-speaking tourists crashed near a national park in southern Utah, killing at least four people and critically injuring up to 15 others, authorities said Friday.

The morning wreck near Bryce Canyon National Park, known for its distinctive landscape of narrow red rock spires, left 12 to 15 people with “very critical injuries,” the Utah Highway Patrol said on Twitter.

Highway Patrol Cpl. Chris Bishop told The Associated Press that he expected the number of injured to be higher.

The tour bus with 30 people aboard crashed near a highway rest stop about 7 miles (11 kilometers) from the park entrance. It’s not yet clear what caused the crash.

Highway Patrol photos show the top of a white bus smashed in and one side peeling away as the vehicle rests mostly off the side of a road near a sign for restrooms. Authorities were tending to people on the road, and others stood around covered in shiny blankets, the photos show.

Bishop said injured victims were sent to three hospitals. One of them, Intermountain Garfield Memorial Hospital, said it received 17 patients.

A spokesman for the small hospital in the tiny town of Panguitch tweeted that three people were in critical condition, 11 in serious condition and three in fair condition. Lance Madigan says Intermountain has sent two helicopters and two planes to help transport victims.

Patients also were being taken to Cedar City and St. George, Bishop said.

Bryce Canyon has the world’s largest concentration of irregular columns of rock, called hoodoos, according to the National Park Service website. The park, about 300 miles (480 kilometers) south of Salt Lake City, draws more than 2 million visitors a year.