Uvalde Police Chief Daniel Rodriguez said U.S. Border Patrol agents saw the truck speeding Wednesday night on a highway outside of Uvalde and began pursuing it, San Antonio TV station KSAT reported.
The police chief said the truck eventually crashed into a large tractor-trailer and another vehicle near downtown Uvalde. He said all of the dead and injured were in the pickup truck.
The Texas Department of Public Safety was investigating the wreck.
Uvalde was the site of a school shooting on May 24 at Robb Elementary School where a gunman killed two teachers and 19 students inside a fourth grade classroom.