HOUSTON - The body of a National Guardsman who had gone missing after a haunting Facebook post was found downstream from where his overturned truck had been located earlier.

Darren Charles Mitchell, 21, from Navasota, is now officially one of five people killed by the latest round of flooding in Texas and Kansas. At least two people were still missing on Sunday after torrential rain in Texas and Kansas flooded rivers and washed out roads.

Mitchell had called his family on Thursday to say he was trapped in flood waters on Highway 105 just outside Brenham on Thursday, reports CBS affiliate KHOU in Houston.

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"(My brother) just said he was all right and he made it out of the truck," Ro Mitchell said.

However, shortly after, he posted a picture on Facebook showing floodwaters rising outside his truck, along with a now-tragic message.

A photo posted to Facebook on Thursday, May 26, 2016 by Darren Mitchell, who went missing amid flash flooding near Brenham, Texas. KHOU

Lashandoe Smith, who said she watched in horror when Mitchell's truck was swept into the water, filled in the blanks Friday when she returned to the scene.

"And he got out of his truck, he got in the bed of his truck, he got back out, on top of his truck, and then all of the sudden he got back in his truck. And like maybe 10, 15 minutes after he was in his truck, it just flipped and he topsided into the water," Smith said as she choked back tears. "It just disappeared. Once it flipped, you didn't see tires, his truck, nothing. It just tumbled over."

An undated photo shows Devon Cooley, 11. KWCH

In Kansas, the search for Devon Cooley, a missing 11-year-old boy, was suspended late Saturday because of darkness and fatigue of first responders, according to Wichita Fire Department battalion chief Scott Brown. The boy was swept away in a swollen creek on Friday night.

"We are more in body recovery mode than rescue," Brown said. Recovery efforts would resume at first light on Sunday, he said.

Near Austin in Travis County, Texas, officials planned to resume aerial searches on Sunday for two missing people whose vehicle was swept off a flooded roadway after the area got 9 inches of rain this week, said emergency services spokeswoman Lisa Block.

The threat of severe weather had lessened in Texas over the long Memorial Day holiday weekend and the focus now is on homes that could be flooded by slowly rising waters. Evacuation orders were issued on Saturday for parts of two Texas cities along the Brazos River near Houston.

"The skies are clear and things look good. But we want to make sure people understand that we are not out of the woods yet. We have to keep an eye on water that's coming through our bayou system," said Francisco Sanchez, a spokesman for the Office of Emergency Management in Harris County, where Houston is located.

In Washington County, Texas, located between Austin and Houston, County Judge John Brieden said the bodies of another missing motorist besides Mitchell were found Saturday in separate parts of the rural county. The body of Pyarali Rajebhi Umatiya, 59, of College Station, was found in a submerged vehicle.

That brings to four the number of people who have died in the county after more than 16.5 inches of rain fell in some places on Thursday and Friday. The downpour washed away mobile homes and flooded other structures. Authorities performed more than 50 water rescues.

The two other deaths in the county were Lela Holland, 64, of Washington, Texas, whose mobile home was swamped by floodwaters, and Jimmy Wayne Schaeffer, 49, of Brenham, who was swept away after driving his truck into high water.

The rising water in several Houston-area rivers and creeks prompted Harris County officials to ask about 750 families in the Northwood Pines subdivision to voluntarily evacuate their homes and apartments on Saturday. Officials also warned residents living near the west fork of the San Jacinto River, north of Houston, that rising waters were likely to flood homes, even those that are elevated, Sanchez said.

In Fort Bend County, southwest of Houston, officials warned residents the Brazos River was likely to rise to the highest level ever recorded in the county, which county Judge Robert Hebert called "a serious incident."

The city of Simonton issued a mandatory evacuation for most of its 800 residents, said Mayor Louis Boudreaux.

Rosenberg, also in Fort Bend County, issued its own mandatory evacuation of some homes near the Brazos River. The evacuation order was to take effect at 2 p.m. Sunday. The city has a population of 34,000.

On the U.S. east coast, Tropical Storm Bonnie formed Saturday afternoon about 125 miles from Charleston, South Carolina, and was moving northwest near 10 mph with top sustained winds of 40 mph, forecasters said.

Bonnie is the season's second-named tropical storm, emerging just four days before the official start of the Atlantic hurricane season, the National Hurricane Center in Miami added. No evacuations have been ordered at this time. The center said a tropical storm warning is in effect from Savannah River to the Little River Inlet in South Carolina and that Bonnie's extended system was dumping rain already in coastal areas.