EAST OF RIO GRANDE CITY - Environmental inspectors are investigating whether a small grass fire that erupted Friday near the tiny community of La Casita spread toxic fumes around the area.

The blaze -- which broke out just before noon near the intersection of Ranch Road 1430 and Expressway 83 - tore through 20 acres and an illegal dump site, San Isidro Deputy Fire Chief Mingo Hinojosa said.

Investigators from the Texas Commission on Environmental Quality were called out to test if nearby air had been tainted by smoke from burning tires and debris. But firefighters encountered only one home in the vicinity.

They were able to extinguish the blaze before it threatened the mobile home, Hinojosa said.

Starr County as well as Hidalgo and Cameron counties remains under a burn ban as dry conditions and high winds continue throughout the region.