Texas mom, two kids among those missing after floods

(CNN)The McComb family is not giving up hope.

Laura and Jonathan McComb and their two children -- Leighton and Andrew -- were at a cabin in Wimberley, Texas, on Saturday night when the skies opened, dumping record-breaking rains. Water soon swept the house downstream. Jonathan McComb was found, but the whereabouts of his wife and children remain a mystery.

"We never lose hope," said his father, Joe McComb. "But I think reality is setting in that there is probably a good chance that it might not be the outcome we're hoping for. But you never give up hope."

He said he suspects a loose tree fell and knocked his family's cabin off its pilings, eventually causing it to be swept downriver.

The McComb family

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"I don't know how many miles downriver ... the house went," Joe McComb said. "When the bridge hit the house, it took the top part of the house off. That's when all the family members got scattered."

As the house was moving, Laura McComb called her sister, Julie Shields.

"A little after 1 o'clock in the morning, she called me and said: 'I just want you to know the ceiling has caved in, and the house is floating down the water, and tell Mom and Dad that I love them. I love you, and pray,' " Shields told CNN's "Anderson Cooper 360."

She described her sister as a good wife, a loving mother and as someone who is loved.

At least 31 people have died as a result of the storms that have ravaged parts of Texas, Oklahoma and northern Mexico since the weekend.

And 13 people are still missing, including 11 in Hays County -- not far from the Texas capital of Austin. The other two missing are an elderly couple in Houston, the mayor's spokeswoman said.

Houston hammed by rain

More than 11 inches of rain fell in some spots of Houston overnight into Tuesday -- inundating byways and highways, slowing first responders, knocking out power and generally bringing the southeast Texas metropolis to a standstill.

According to the authorities in Houston, five people died and at least two more are missing.

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"We got hammered," Houston Emergency Management Coordinator Rick Flanagan told CNN's "New Day," echoing sentiments by many others in the region in recent days. "We had cars that were stranded, mobility was stopped ... signals didn't work. It was just a madhouse."

It still is. While the sun appeared Tuesday, more rain remains possible. And even though some parts of Houston were "high and dry," others were not, Mayor Annise Parker said.

"The sun is shining out here right now and the city is slowly getting back to normal, but this is a little bit of a situation of a tale of two cities. Much of Houston was unaffected by the weather, but the parts that were affected by the weather were very severely hit," she told reporters.

Underpasses, patches of highways and areas near waterways such as the San Jacinto River, Cypress Creek and Buffalo Bayou, already strained by weeks of heavy rain, remain inundated.

"The defining feature of Houston is the small rivers that run through the city," Parker said. "Many of them went over their banks and began to flood neighborhoods."

The result of the flash floods and river overruns is "lots and lots of abandoned cars" and large pools of standing water, making for a logistical and traffic nightmare in the nation's fourth most populated city.

The mayor said that as many as 4,000 properties in Houston may have suffered "significant damage," although the assessment is complicated by all the water.