A wildfire blamed on a fallen power line in the Rio Grande Valley spread to 50,000 acres Wednesday, forcing hundreds from their homes.
A 40-mile stretch of U.S. Highway 281 -- the main route north out of the area -- was reopened in both directions about 6:30 a.m., said Hidalgo County spokeswoman Cari Lambrecht.
The fire that began Tuesday afternoon was 50 percent contained by Wednesday morning.
Earlier, firefighters estimated the blaze as 18 miles wide with flames leaping 40 feet into the air.
At least four homes were destroyed, and bulldozers uprooted grass near the Hidalgo County Jail and an elementary school in hopes of stopping the encroaching flames, authorities said at a news conference early Wednesday.
At least 500 people were evacuated, but no injuries had been reported, The Monitor in McAllen reported.
"Right now, our priority is to save lives," Hidalgo County Judge J.D. Salinas said.
Deputies went door-to-door through the area Tuesday night to alert residents to the threat. Edinburg North High School was opened as a shelter, Hidalgo County spokeswoman Cari Lambrecht said.
The wildfire began after President Bush made federal aid available to 70 percent of Texas counties last weekend. Wildfires scorched 133,000 acres across the state Friday.