The third vehicle kept going when agents encountered it, and a sheriff's deputy took over the chase prior to the fatal crash, the border patrol said.
Four people were pronounced dead at the scene, officials said.
Boyd said the driver of the SUV survived and was taken into custody. Dimmit County Sheriff Marion Boyd said the SUV was traveling at speeds over 100 miles per hour before it crashed near Highway 85, ejecting some of those inside. Boyd tells San Antonio television station WOAI a driver and one passenger are believed to be US citizens.
Boy believes the driver was scouting the area to try and pick up immigrants. "It's a problem. This is, I think, a flawless example of why our borders need to be secure".
The other 12 passengers were undocumented immigrants, Boyd said.
Four people died at the scene and a fifth died later, KSAT 12 television of San Antonio reported.
Boyd credited "good police work" for the reason why deputies started pursuing the vehicle adding that Boyd said human smuggling was a "real problem" in the area.
5 immigrants killed in rollover crash in Dimmit, Texas.
Yolanda Choates, a US Customs and Border Protection spokeswoman, directed questions to the Dimmit County Sheriff's Office.
Multiple people inside the Suburban were ejected as the vehicle rolled, according to the Texas Department of Public Safety.