A massive amount of rainfall in the metropolitan Houston area has blocked roads, left drivers stranded on Interstate freeways, and destroyed homes.
Between six inches and a foot of rain was reported to have fallen in the area by early morning Tuesday.
The White Oak Bayou in Houston is rising rapidly and spilling over onto highways, and could reach a level last seen in 2008 as a result of hurricane Ike, said the National Weather Service. In one town alone (the Texas Hill country town of Wimberley), some 400 homes were reported destroyed, with a dozen or more people reported missing.
Earlier on Monday a tornado had hit Ciudad Acuna in Mexico, killing at least 13, as a series of powerful storms swept across the southern Great Plains.
Evacuations are also underway in Austin, the Texas state capital.
Up to 100,000 homes are reported to be without power.
Most flood loss to homes in the US devolves to the Federal Emergency Management Agency (FEMA), although the private sector could be on the hook for significant motor-related losses.