Published: Aug 10, 2010 4:52 PM EDT
Updated: Aug 10, 2010 1:53 PM EDT

CEDAR CITY, Utah (AP) - A tour bus carrying Japanese sightseers from Las Vegas to a national park in Utah crashed on Interstate 15, killing three passengers and sending a dozen others to hospitals, authorities said.

Several of the bus passengers were flown to the Salt Lake City area for emergency care, officials at Utah's trauma centers said.

Two men and two women were in critical condition at

Intermountain Medical Center in the Salt Lake suburb of Murray, said hospital spokesman Jess Gomez.

Two other women in critical condition were at University Hospital. It wasn't immediately known where other bus occupants were taken, and none has been identified.

The bus was heading to Bryce Canyon National Park when it veered into a median and rolled over about 6:40 p.m. Monday on I-15 about four miles north of Cedar City, Utah Highway Patrol spokesman Cameron Roden said.

Roden said investigators want to ask the driver what caused him to swerve.

Trooper James Keller told The Spectrum of St. George at least two passengers were ejected from the van-sized bus, and one passenger trapped inside was killed.