Thunderstorms backed by racing winds set off a string of tornado warnings in parts of southeast Texas on Sunday and into Monday morning, according to the National Weather Service.
The strong storms, along with intensifying wind shears, may have produced a tornado, the agency said.
At least 100 homes were reported damaged late Sunday in San Antonio, the National Weather Service told CNN. Officials plan to send out teams Monday morning to survey losses.
Nearly 40,000 customers in the San Antonio area remain without power, CPS Energy said. Two minor injuries were reported, officials said.
In Thrall, Texas -- 120 miles northeast of San Antonio -- strong storms after midnight Monday caused a train to partially derail, the weather service told CNN.