Authorities say the man and his two sons were boating near Atascocita Place and Misty Cove when their boat started having engine problems and the man fell into the water.
"When he fell out, the boat apparently, from what we understand, came back around and over the complainant," Senior Officer Alvin Steelman said.
Witnesses told police they saw the boat going straight, then suddenly veer into a sharp turn. The children on board told police they heard a loud pop right before it happened.
The two kids, who were both wearing life jackets, were stuck in the boat, spinning in circles.
"One was just sitting down and the other one -- the little boy -- was standing up screaming and hollering, 'My dad's fell overboard, my dad's fell overboard!'" nearby resident Don Seagraves said.
Another boater came along and told the oldest boy to turn the key off, which stopped the engine.
"It actually was an off-duty firefighter who stopped. He was able to get the boys and bring them into shore," Capt. Alvin White said.
Nearby resident Mary Seagraves took the kids into her home while searchers recovered their father's body.
"The older boy, he was very brave. But the little one, every time he tried to tell me something, I'd say, 'What happened?' and I could see the tears in his eyes," Seagraves said.
Houston Fire Department crews found the father floating nearby about 10 minutes later. His name has not yet been released, but we're told he was in his 40s.
Police aren't ruling the death a drowning because of the mechanical failure. They're calling it an accident on the water. If it had been a drowning, it would have been the first on Lake Houston in more than two years.