CAMPBELLTON, Texas (AP) - Investigators say a broken drive shaft likely caused a bus to veer off a Texas highway, killing two passengers and injuring 40 other people.

Texas Department of Public Safety spokeswoman Tela Mange said Wednesday that a preliminary investigation shows the drive shaft came apart and fell off the Americanos USA bus as it was driving Tuesday morning on Interstate 37 about 45 miles miles from San Antonio.

The driver lost control of the bus and it spun into the center median and flipped onto its side.

A male and female passenger were killed, and two passengers remained hospitalized in critical condition Wednesday.

(Copyright 2010 by The Associated Press. All Rights Reserved.)

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