A passenger car driver ran a red light and caused a school bus crash that injured 15 children on the bus, the bus driver and a child in her car, police and school officials in Las Vegas said Friday.

The 70-year-old driver of the Ford Taurus was killed and the 10-year-old girl who was with her was seriously injured following the Thursday morning crash at a busy crossroads several miles northeast of downtown, authorities said.

The girl was in critical condition Friday at University Medical Center in Las Vegas, hospital spokeswoman Danita Cohen said.

Forty children were aboard the bus, and 14 received moderate injuries, Clark County school police Capt. Ken Young said Friday. School officials said Thursday that 48 children were on the bus, and 15 were injured.

That tally included the bus driver, identified by Las Vegas police as Dawn Rice, 40, of Las Vegas. She also was treated at a hospital and released, Young said.

Clark County school transportation chief Shannon Evans credited Rice, a driver with 13 years' experience who had been temporarily assigned to the middle school bus route, with immediately radioing for help after the crash.

"That driver's first words out of her mouth were, 'I need help. My kids need help. Please come help my kids,' " Evans told reporters.

Children described being tossed from their seats when the bus veered through a fence and toppled on its side in a dusty vacant lot.

Children are taught at least twice a year how to evacuate through escape hatches on the roof and the back of a bus in case of an emergency, Evans said.