Texas ? A wildfire blamed on a fallen power line in the Rio Grande Valley spread to about 25,000 acres Wednesday, forcing hundreds from their homes.

A small grass fire near Laredo also caused a power plant to shut down as a precaution for about two hours and led the state’s electric power grid to import power from Mexico for a time.

The Rio Grande Valley fire, which started Tuesday afternoon, was 50 percent contained by Wednesday evening. Earlier, the Texas Forest Service estimated the blaze covered about 50,000 acres but a view from the air showed it to be about half that size, spokeswoman Sandra Taylor said.

Still, the fire covered an area about 20 miles long and 2 miles wide, she said.

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 least 500 people evacuated. There were no reports of injuries.