The U.S. Geological Survey said the 3.7 magnitude quake happened at 4:51 a.m., about 45 miles southeast of San Antonio in South Texas.
The quake was detected about 6 miles southwest of the Karnes County town of Falls City, near the line with Wilson County. Some Wilson County residents reported feeling the quake.
The epicenter was at a depth of about 3.1 miles.
Texas occasionally has earthquakes.
In the Texas panhandle, a minor earthquake was felt by some people in Amarillo on March 30, 2002. The Amarillo area also recorded seven minor earthquakes in 2000.