SALT LAKE CITY (AP) - Five people remain in critical condition after a bus crash that killed four Chinese tourists and injured dozens more near a national park in Utah.

  

Utah Highway Patrol Sgt. Nick Street said Friday evening that the bus originated in Southern California, and the tourists on board were natives of mainland China.

  

Up to 15 people suffered injuries that were originally considered very critical, but the condition of several passengers has improved in the hours since the crash.

  

Authorities are investigating what caused the bus to careen into a guard rail Friday morning on highway winding through otherworldly spires of red rock near Bryce Canyon National Park in southern Utah.

  

The names and hometowns of the victims were not immediately released.