The incident left two people dead. A group of seven illegal immigrants from Guatemala are in custody after the shooting, which took place near La Joya, Texas.
The Texas Department of Public Safety said the truck had what looked like a "covered" drug load in its bed. The truck was already being chased by Texas Parks and Wildlife Department rangers. They called for help. A state police sharpshooter was the first to respond. He fired to disable the pickup truck.
The Guatemala consulate in McAllen and the Texas state police are still investigating the incident. The officer is on administrative leave, a common protocol in police-involved shootings.
Shootings along the border have increased since 2010.