Water from the Blanco River floods a shopping center Sunday in San Marcos, Texas. Recovery teams were resuming the search today for 12 people who are missing after the river carried a vacation home off its foundation.

WIMBERLEY, Texas — Recovery teams were resuming the search early today for 12 members of two families who are missing after a rain-swollen river in Central Texas carried a vacation home off its foundation, slamming it into a bridge downstream.

The hunt for the missing picked up after a holiday weekend of terrible storms that dumped record rainfall on the Plains and Midwest, caused major flooding and spawned tornadoes and killed at least eight people in Oklahoma and Texas. More than 1,000 homes have been damaged or destroyed in Texas, and thousands of residents are displaced.

Authorities were also searching for victims and assessing damage just across the Texas-Mexico border in Ciudad Acuna, where a tornado Monday killed 13 people and left at least five unaccounted for.

Texas Gov. Greg Abbott declared disasters in 37 counties, allowing for further mobilization of state resources to assist.

“You cannot candy coat it. It’s absolutely massive,” Abbott said after touring the destruction.

The worst flooding damage was in Wimberley, where the vacation home was swept away, a popular tourist town along the Blanco River in the corridor between Austin and San Antonio.

Trey Hatt, a spokesman for the Hays County Emergency Operations Center, said Monday night that the “search component” of the mission was over, meaning no more survivors were expected to be found in the flood debris.

Witnesses saw the swollen river push the home off its foundation and smash it into a bridge. Only pieces of the home have been found, Hays County Judge Bert Cobb said.

One person rescued from the home told workers that the other 12 inside were all connected to two families, Cobb said. Young children were among those believed to be missing.

The Blanco crested above 40 feet — more than triple its flood stage of 13 feet. The river swamped Interstate 35 and forced parts of the busy north-south highway to close. Rescuers used pontoon boats and a helicopter to pull people out.

Hundreds of trees along the Blanco were uprooted or snapped, and they collected in piles of debris up to 20 feet high.

Flooding wreaked havoc late Monday afternoon in Austin, where emergency crews responded to more than 20 high-water rescues, and later in Houston, where the National Weather Service declared a flash flood emergency and an announcer at the Houston Rockets game asked fans not to leave because of severe weather. Harris County Flood District, which includes Houston, advised residents not leave their homes early today after the weather service issued a flash flood warning for parts of the county.