KELLER (CBSDFW.COM) – A shallow, narrow neighborhood lake cuts through the Highland Oaks subdivision in Keller. It attracts kids with fishing poles in the summertime, and wildlife on the banks. But it turned from lively to lethal in just one night recently.

“They said really, they’re dead. There’s piles and piles and piles of them and I came over and the whole pond was just covered and they were all just going down there,” says resident Lindsey Malone.

Fish, big and small littered the lake. “The smell of death was unbelievable,” said Malone.

What concerned residents even more was no one appeared to have an answer to what happened. Game wardens, environmental quality commissioner and city environmental services–no one knew.

“We want to know that the water’s clean and safe and really just that the kids, the dog, anybody can go near it.”

On Friday, the subdivision’s management company said an attempt to kill something else in the water may have played a part. Algae had exploded in the extreme hot temperatures, and an effort to control it suddenly with chemicals, may have caused oxygen levels to change, water to turn over, and fish and shellfish to die.

“Oh it was a surprise. And we got our lake company to come out right away and they told us it was water turnover from hot temperatures to cold temperatures,” said HOA board member Betty Nguyen.

The homeowners association had the fish cleaned up, and said there’s no danger to any other wildlife or anyone in the neighborhood.