Update, 11:35 p.m. EDT: 

Update, 10 p.m. EDT:  In Texas,  a state of emergency has been declared in 37 counties, Gov. Greg Abbott said, according to CNN.  In Hays County, Texas, 12 people were still missing. The missing were from families who had gathered for the long weekend, according to Ken Bell, emergency coordinator for San Marcos, one of the cities hardest hit by the storms and flooding. The group likely includes children, Bell said. Hays County still has Internet problems, and cellphone networks have been overwhelmed.

Update, 3 p.m. EDT: Texas Gov. Greg Abbott declared a state of emergency in 24 of the state’s counties, according to Reuters. And the National Weather Service confirmed the sighting of a tornado in Blanco County, while warning of twisters in other counties, the Austin American-Statesman reported.

Original Article Appears Below

Heavy rainfall on Memorial Day could elevate the risk of flash flooding in parts of Oklahoma and Texas, still grappling with the devastation of deadly weekend storms. Five people in those two states and Mississippi were killed in the storms, while thousands more were displaced and hundreds of homes were destroyed as the severe weather led to record-setting flash floods.

With storms looming over the region, the National Weather Service issued flash flood warnings Monday for a number of counties in Texas, Oklahoma and Mississippi, as well as Louisiana. In south-central Texas, the weather service warned, “Only an inch or two of rainfall could quickly lead to more flash-flooding or river-flooding concerns.”

The weather service says rainfall amounts of 1 to 4 inches are possible, with as many as 5 inches in isolated areas.

Flooding was especially brutal over the weekend in Hays County, Texas, where local officials said a dozen people were missing, according to CNN. As many as 400 homes in the county were washed away, and more than 1,000 homes in the area were damaged. Flowing through the county seat of San Marcos, the Blanco River broke its previous flood record of 33 feet by a 7-foot margin. Before the flooding began, it was just a little more than 5 feet deep. One man’s body was recovered from the river.

“We do have whole streets with maybe one or two houses left on them and the rest are just slabs,” a Hays County official said.

Among the fatalities blamed on the extreme weather were a firefighter who died Sunday while attempting a water rescue in Claremore, Oklahoma, and a high-school student who died Saturday while driving home from a prom in Devine, Texas.

About a thousand people were evacuated near a dam at Lake Lewis, roughly 50 miles north of Houston. Authorities there worried heavy rain could cause the dam to fail. A county representative told the Chicago Tribune it wasn’t clear when residents would be allowed back home.