CAMPBELL, TX - An Americanos USA bus on Tuesday, March 16, veered out of control on a Texas highway before flipping over, killing two passengers and injuring 40 others on board, the Associated Press reported. 

Investigators have preliminarily blamed the crash on a broken drive shaft that apparently fell off before the bus careened from the right lane toward the median and spun wildly. The investigation is ongoing. 

Dallas-based Americanos USA LLC operates a fleet of 137 motorcoaches and maintains alliances with Greyhound Lines, Grupo Estrella Blanca and Crucero USA. 

The crash occurred along Interstate 37, about 45 miles from San Antonio. The bus was bound for Mexico, with planned stops in Falfurrias and McAllen, Texas. Some of the passengers were students heading for spring break. 

The two passengers killed were Christina Lozano Campos, 62, of Lewisville and Efrain Dominguez-Valenzuela, 27, of Brownsville. Two others remained hospitalized in critical condition on Wednesday, March 17. The other 38 people traveling in the bus were either hospitalized in stable condition or had been treated and released. 

Americanos USA has a good federal safety record, AP reported. Before the accident Tuesday, the company's vehicles were involved in 10 accidents in three states in the past 30 months, according to Federal Motor Carrier Safety Administration records. 

In the past two years, inspectors placed Americanos USA vehicles out of service following 11.2 percent of their inspections. That's about half the national average of 22.3 percent, AP reported. Moreover, inspectors placed the company's drivers out of service after just 1.8 percent of inspections -- a much lower rate than the national average of 6.6 percent.