A tour bus carrying 45 passengers overturned along an icy interstate Saturday, killing a woman and an 8-year-old boy and injuring dozens of others, authorities said.

The bus crashed about 10:20 a.m. Saturday along Interstate 35, just south of Pauls Valley in Garvin County, OHP Lt. Stewart Meyer said.

"Preliminary indications are that it was due to road conditions," Meyer said. "They're still investigating."

The bus apparently flipped and skidded on its top before coming to rest on its side, said Brent Thompson, a spokesman for the Pauls Valley Fire Department.

The driver of the bus, Miguel Esquada of Fort Worth, Texas, said through an interpreter that a car pulled in front of him suddenly, he hit the brakes and the bus began to overturn.

The 8-year-old boy, who was sitting in the middle of the bus, was thrown through a window and the bus fell on top of him, Esquada said.

The other victim was riding in the back of the bus.

Thompson said the boy was alert and conscious when firefighters arrived at the scene.

"We were actually able to talk to the little boy while he was trapped under the bus," Thompson said. "He was definitely wanting out from under there."

Thompson said firefighters deployed air bags to lift the bus and were able to remove the boy.

"As we started lifting, he was still with us, but shortly thereafter he lost consciousness," Thompson said.

The other woman was dead at the scene, Thompson said.

He said some of the more serious injuries included broken bones, severe lacerations and internal injuries.

One passenger with critical injuries was taken by helicopter to the OU Medical Center in Oklahoma City. At least two other passengers were taken by ambulance to Norman Regional Hospital, Lt. Meyer said.

Tony Malaska, a spokesman for Pauls Valley General Hospital, said most of the 45 passengers were treated for minor injuries.

The bus was registered to El Conejo Bus Lines and was traveling from Kansas to Dallas, said Ana Gonzalez from El Conejo's Dallas office. Gonzalez said she could provide no additional details.