Flash flooding from record rains in Texas and Oklahoma left at least three people dead and destroyed hundreds of homes, authorities said Sunday, warning of more wild weather to come.

In the Texan city of San Marcos, residents were ordered to evacuate their homes in the early morning as flood waters rose menacingly around them, following torrential rain that turned normally bone-dry streets into meandering rivers.

Cars and trucks were submerged and people used inflatable lounge chairs to float down the street, in surreal scenes.

As many as 400 homes in the surrounding area had been destroyed, authorities said, and San Marcos opened temporary shelters to host residents who could not return home.

"Evacuation messages have gone out via reverse 911 and police officers and firefighters are going door-to-door to notify residents in affected areas," the city said in a statement.

It noted that the fast-rising Blanco River had broken record levels set in the 1920s.

Fire Marshal Ken Bell told CNN that at least one person was confirmed dead and crews were searching for three missing people.

At least two people also died in Oklahoma, which is located to the north of Texas.

A firefighter in the town of Claremore died when he was swept into a storm drain while trying to help a resident in floodwaters, CNN said, and a woman in Tulsa died after her car hydroplaned.

The National Weather Service warned that strong to severe thunderstorms were expected across a large stretch of the central and southern plains toward the Mississippi River Valley.

"Isolated tornadoes, hail and damaging winds are all possible," it added, noting that flash flooding was also forecast from central Iowa into southern Texas, set to get the brunt of the downpours.