UPDATE 7 p.m.
Starr County officials said firefighters contained the blaze, according to a social media post the county made shortly before 7 p.m.
Two structures and several vehicles have already been caught by a massive brush fire in northwestern Starr County, but no injuries have been reported.
The fire broke out north of La Gloria and is traveling southeast, according to a social media post shared by the county. Residents near the area were instructed to prepare to evacuate.
Texas Department of Public Safety troopers are assisting with the evacuation process, according to San Isidro Fire Department Chief Bernabe Benavidez. Evacuations are temporary, not overnight, the chief added.
A portion of FM 755 near La Gloria remained shut down as of 6 p.m.
The fire is estimated to have spread to about 150 acres in La Gloria. Several fire departments from the Rio Grande Valley are assisting.
Chief Benavidez anticipates having the fire under control in about two to three hours, or about 8 or 9 p.m.