CAMPBELLTON, (March 16, 2010)—Two people died and 30 other people were sent to hospitals after a tour bus bound for Mexico with 40 passengers aboard rolled and ended up in the median of Interstate 37 in South Texas.

The driver of the bus told investigators "she heard a loud pop" before the crash on Interstate 37 southbound, about 45 miles south of San Antonio.

Texas Department of Public Safety spokesman Tom Vinger said investigators suspect equipment failure may have caused the crash.

Vinger told The Associated Press, "The driver said she heard a loud pop and then lost control of the vehicle."

Emergency officials in Atascosa County say the bus veered off the right side of the road, and then back across the interstate and into the median, where it landed on its side.

The bus windows were shattered, and luggage, pillows and purses littered the median.

Vinger said the bus was carrying Mexican and American passengers from San Antonio to Matamoros, Mexico, near the U.S. border, with a scheduled stop in Falfurrias.

The bus was operated by Americanos USA, a subsidiary of Dallas-based Greyhound Lines.

The accident happened in overcast conditions with temperatures in the mid-50s.