Dozens of roads have been rendered impassable in San Antonio and surrounding county as heavy rain caused floods across central Texas.
The floodwater also knocked out power supplies to some 12,000 customers, according to to CNN.
The National Weather Service (NWS) has flood warnings in force for five rivers in the San Antonio area and is warning drivers in affected areas to stay put.
A tornado briefly touched down in the suburb of Live Oak causing minor damage to buildings and trees but is no longer a threat, the NWS reported.
More top news
Heavy showers set to spread into western areas tomorrow.
Andy Murray is Britain's last hope of a 2015 Wimbledon win after overcoming an apparent shoulder injury to beat Italy's Andreas Seppi.
New Tour de France time-trial record set after Australian Rohan Dennis raced into the lead during Stage one of the competition.