Two people died and 13 were injured when the van they were traveling in towards Mexico rolled over on a highway near San Antonio.

The accident reportedly occurred when the right rear tire of the 15-passenger van was blown out according to the Department of Public Safety. Investigators said they couldn’t determine how many passengers were wearing seat belts.

The van crashed on Interstate 35 about 30 miles southwest of San Antonio near the town of Natalia. The van reportedly veered left when the tire blew out. The vehicle hit the interstate's median, where it rolled and came to rest. It never crossed into the northbound lanes, police investigators said.

The crash occurred at about 3 a.m. said Lt. Steven Tellez, a spokesman for the Texas Department of Public Safety in San Antonio. All the passengers were relatives from the Fort Worth area.

The vehicle with Texas plates was registered to a 55-year-old man who died in the crash. The other victim was a 15-year-old boy. The injured were rushed to San Antonio's University Hospital to receive treatment. Three were flown by medical helicopter in critical condition.