The National Weather Service issued a new flash flood warning on Wednesday for Houston as the fourth most-populous U.S. city searched for bodies from deadly storms that turned neighborhoods into lakes.

Near Dallas, police evacuated residents living near a dam that was poised to burst on Wednesday due to surging floodwaters as emergency officials searched for bodies from storms that killed at least 17 in Texas and Oklahoma.

Water was topping the Padera dam, about 25 miles southwest of Dallas, and police in Midlothian said they have called on people living downstream to evacuate and move livestock to higher ground in case the structure gives way.

The death toll was set to rise with numerous people still missing in Texas after the storms slammed the states during the Memorial Day weekend, causing record floods that destroyed hundreds of homes, swept away bridges and stranded more than 1,000 motorists on area roads.

“Right now we still have a lot of our neighborhoods underwater,” Michael Walter, a spokesman for Houston’s Office of Emergency Management, told NBC’s “Today” program.

About 11 inches (28 cm) of rain fell in Houston on Monday while parts of Austin have been hit by as much as 7 inches (18 cm). Helicopter crews in both cities plucked to safety people who had been stranded in cars and on top of buildings.

President Barack Obama said on Tuesday he had assured Texas Governor Greg Abbott that he could count on help from the federal government as the state recovers from the floods. Abbott has declared a state of disaster in at least 40 Texas counties, including Harris County, which includes Houston.