Reuters –  Texas Governor Greg Abbott on Monday likened the ferocity of flash flooding that left at least five people dead in Texas and Oklahoma to a tsunami, and authorities said a dam had given way in a state park.

Abbott declared states of disaster in 24 counties and flew over the area south of Austin to assess the damage caused by tornadoes, heavy rainfall, thunderstorms and flooding that forced evacuations and rooftop rescues and left thousands of residents without electricity.

"This is the biggest flood this area of Texas has ever seen," Abbott said.

"It is absolutely massive - the relentless tsunami-type power of this wave of water," he said.

He described homes that were "completely wiped off the map" by the dangerous weather system that struck Texas and Oklahoma.

Police in DeVine, Texas, south of San Antonio, said the dead included an 18-year-old girl whose car was swept away by flood waters as she returned home from her high school prom.

Authorities in Bastrop County, on the southeastern outskirts of Austin, said on Twitter that Lake Dam had failed in Bastrop State Park, forcing several rescues but causing no injuries.

The National Weather Service issued a flash flood emergency for Houston, where more than 60,000 area residents were without power, according to CenterPoint Energy.

Accuweather.com said more rain was forecast through Monday across eastern Texas and Oklahoma, bringing flash floods, tornadoes and winds of more than 65 mph.

The National Weather Service reported 4.5 inches of rain fell in 90 minutes at Marquette, in central Kansas, washing out roads.

The bodies of a 14-year-old boy and his dog were found in a storm drain in the Dallas suburb of DeSoto on Monday, police said. Two other people killed in the storm were described as an unidentified man found dead in San Marcos, Texas, and a firefighter who was swept into a storm drain in Oklahoma.

The New York Times said a Tulsa, Oklahoma, woman died on Saturday after her automobile hydroplaned on a highway.

Twelve people were listed as missing in Texas, including eight from an extended family from Corpus Christi who were vacationing in a Wimberley home that was washed into the raging Blanco River, according to officials and the family's church.

A curfew in Wimberley and San Marcos was extended for a second night on Monday, Hays County officials said.

Parts of the area have received more than 1-1/2 feet of rain since May 1, six times normal May amounts.

The governor's office said the severe weather could continue through the week.