WIMBERLEY, Texas – Recovery teams resumed the search Tuesday for 12 people who are missing after a rain-swollen river carried a Texas vacation home off its foundation and slammed it into a bridge downstream.

In Houston, authorities recovered three more bodies from the floodwaters – two of them in the city and a third in a vehicle on Interstate 45. That brings to 11 the number of people killed by the storms in Oklahoma and Texas.

The water rose overnight after the area received about 11 inches of rain, much of it in a six-hour period.

Between 500 and 700 homes in surrounding Harris County have sustained some level of damage, according to county flood control district spokeswoman Kim Jackson.

Houston Mayor Annise Parker said officials in the nation’s fourth-largest city would be “on the alert” as the bayous rise.

The search for the missing picked up after a holiday weekend of storms dumped record rainfall on the Plains and Midwest.

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.

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

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

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

Witnesses reported seeing 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 who was rescued from the home told workers that the other 12 inside were all connected to two families, Cobb said Monday night. Young children were among those believed to be missing.

But by early Tuesday, Hays County spokeswoman Laureen Chernow acknowledged discrepancies concerning how many people might have been inside the vacation home. She said officials were not able to confirm whether all 12 were in that house.

“We don’t have that certainty,” Chernow said.

Eight of the missing were friends and family who had gathered for the holiday, said Kristi Wyatt, a spokeswoman for the City of San Marcos. She said three more were members of another family in a separate situation. An unrelated person was also missing, Wyatt said.

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.

The Harris County Flood District, which includes Houston, advised residents not leave their homes early Tuesday after the weather service issued a flash flood warning for parts of the county. Before the sun rose Tuesday, emergency crews used helicopters and boats to help residents evacuate their flooded homes in Webberville, some 15 miles east of Austin.

The storm system also produced reports of tornadoes across the state and was blamed for four deaths: a man whose body was pulled from the Blanco; a 14-year-old who was found with his dog in a storm drain; a high school senior who died Saturday after her car was caught in high water; and a man whose mobile home was destroyed by a reported tornado.

The Oklahoma Department of Emergency Management also reported four fatalities between Saturday and Monday after severe flooding and reports of tornadoes.

In Ciudad Acuna, Mayor Evaristo Perez Rivera said 300 people were treated at local hospitals after the twister, and up to 200 homes had been completely destroyed. The government was talking with families whose homes had been damaged to determine how much assistance would be needed to rebuild the city of 125,000 across from Del Rio, Texas.

“We have never registered in the more than 100 years in the history of this city a tornado,” he said.

By midday, 13 people were confirmed dead – 10 adults and three infants. At least five people were unaccounted for.

The twister hit a seven-block area, which Victor Zamora, interior secretary of the northern state of Coahuila, described as “devastated.”

“There’s nothing standing, not walls, not roofs,” said Edgar Gonzalez, a spokesman for the city government, describing some of the destroyed homes in a 3-square kilometer (1 square mile) stretch.

Gonzalez said late Monday night that rescuers were looking for four members of a family who were believed missing, adding that there were still areas of rubble that remained to be searched. Zamora said rescuers were searching for an infant who was missing after the tornado ripped the baby carrier the child was in from its mother’s hands.

Luis Antonio Hernandez, 37, looked in disbelief Monday at what remained of his house. Three vehicles had smashed through the back, leaving a heap of twisted metal and the smell of gasoline.

Hernandez and his three children had hidden in a bathroom as the tornado sent the cars passing over them. “It’s a miracle that we’re alive,” he said.

Robbins reported from Ciudad Acuna.

Associated Press Writer Mark Stevenson in Mexico City contributed to this report.