LIBERTY, Mo. - A school bus slammed into two vehicles as it approached an intersection Monday morning, killing two people in the cars and injuring 23 elementary students.

Investigators said they don't know why the bus suddenly veered into the cars, which were waiting for a stoplight to change in this community about 15 miles north of Kansas City.

Two children were taken to hospitals with life-threatening injuries. Some of the children suffered head injuries, cuts, scrapes, broken bones and neck injuries, said Laura Fitzmaurice, head of the emergency department at Children's Mercy Hospital in Kansas City. Many were bleeding and crying for their parents.

"One little boy had his teeth knocked out and he asked me if he was going to be deformed,'' said a shaken Vickie Whattoff, one of about 20 workers from a nearby grocery store who responded. "We saw that it was a bus and ran over and started helping kids out.''

The cars were nearly demolished. The victims were identified as David Gleason, 53, of Kansas City, and David Sandweiss, 49, of Liberty, police said. They were the only people in the vehicles.

Police said 23 students were taken to three area hospitals with injuries and the others were taken to the school or released to their parents.

"It's a worst nightmare,'' he said. "This is a tragedy for this community.''

The bus was taking 53 kindergartners through fifth-graders to Ridgeview Elementary School when the crash happened about 8:30 a.m. The students ranged in age from 6 to 11.

The bus driver, whose name was not released, was being treated at a hospital Monday. Taveau said the driver was a seven-year veteran driver who had "an impeccable record.''

Immediately after the crash, dozens of workers at nearby businesses rushed to the scene to help the children off the bus.

"We were standing outside on a break when we heard a loud boom and saw a big cloud of dust,'' said Whattoff.

Many of the workers sat with the children, she said, comforting them while waiting for rescue crews to show up.

By Bill Draper, AP