The governor of Texas has declared states of disaster in 24 counties, citing the severe weather and flash flooding that have killed at least three people.
In issuing the disaster declarations on Monday, Texas Gov. Greg Abbott said, "The state of Texas has taken brisk action in dispatching all available resources to aid those affected by this severe weather system.”
There are now 37 counties declared disaster areas in Texas.
On Monday, the death toll after recent heavy rains and other severe weather reached four dead after what Milam County Sheriff David Greene called a "pretty destructive" tornado killed a man while injuring four people, destroying four homes and damaging 10 to 15 others on about 4 p.m. on Monday. Earlier in the day, a 14-year-old boy and his dog were found dead in a suburban Dallas storm drain. Authorities said at least one other person was killed in Wimberley in the Blanco River Valley flooding on Sunday, and a high school senior died Saturday night after her car was caught in high water.
Twelve people are missing from a house that washed down the Blanco River and smashed into a bridge in the center of the community.
Abbott says the damage caused by flash flooding in Central Texas is "absolutely devastating."
He flew over the area south of Austin to assess the damage caused by tornadoes, heavy rainfall, thunderstorms and flooding that forced evacuations and rooftop rescues and left thousands of residents without electricity.
"This is the biggest flood this area of Texas has ever seen," Abbott said.
"It is absolutely massive, the relentless tsunami-type power of this wave of water," he said.
He described homes that were "completely wiped off the map" by the weather system that struck Texas and Oklahoma.
Abbott also flew over parts of the rain-swollen Blanco River on Monday, a day after heavy rains pushed the river out of its banks and into surrounding homes in the small town of Wimberley.
Teams have ended their search for survivors of the flash flood in the Blanco River Valley, said Trey Hatt, spokesman for the Hays County Emergency Operations Center on Monday night.
He said "the search component is over," meaning that no more survivors are expected to be found in the flood debris.
Hatt says recovery operations will begin Tuesday.
The governor's office said the severe weather could continue through the week.
At least 12 people are still missing believed swept away by weekend floodwaters, according local media reports in Austin, Texas, which said the search had been delayed by more storms.
Parts of the area included in the disaster declaration have received more than a foot and a half of rain since May 1, which is six times more than the area typically receives in all of May, according to Accuweather.
Meteorologists said soil was saturated from heavy rainfall over the past three weeks, leading to the dangerous flash floods.
In Oklahoma, a firefighter died Sunday in Claremore, Oklahoma, about 30 miles northeast of Tulsa, while he was responding to a call to help about 10 people trapped in their homes by rising floodwaters, television station KTUL reported.
Al Jazeera and wire services