p>WARRENTON, Ga. – Two toddlers who were reported missing from their home over the weekend were found dead in an algae-covered sewage pond a few hundred yards away Monday after a two-day search.

The cause of death was not immediately disclosed, and Georgia Bureau of Investigation spokesman John Bankhead said it was not known whether the youngsters were the victims of foul play. Autopsies were planned.

Nicole Payne, 2, and her brother, Jonah, 3, were reported missing on Saturday from their lakeside house about 100 miles east of Atlanta. The children’s mother called authorities to report that the toddlers vanished after she went into another room. Police said their mother found the front door open and the children gone.

Bankhead said green algae made it difficult to see the children when authorities first searched the 1 1/2-acre pond, situated at the end of road behind the family’s house.

The pond – part of the city’s sanitation system – is surrounded by a fence, but has several holes where a child could easily get through.

Police Chief Jim McClain said that earlier in the day Saturday, the children got out of the house. He said Nicole figured out how to unlock the front door and gate and left with Jonah at around 4 p.m. A neighbor returned the children a half-hour later, he said.

Authorities said Nicole needed a breathing machine daily and her brother was on medication for an unspecified condition.

On Sunday, agents from the Georgia Bureau of Investigation questioned the children’s mother, Lottie Kain. Authorities said more than one person was given a polygraph test. They would not comment on the tests.

Up to 100 law enforcement officers searched for the youngsters, using heat-seeking devices, infrared radar at night and cadaver dogs. Searchers combed the woods, and divers looked in a lake.

The children’s disappearance shocked and saddened people in Warrenton, a town of narrow, two-lane roads known mostly for the sweet potatoes at Jane’s Restaurant.

Stephanie Johnson, walking with her 22-month old daughter, Ella, said she had been praying for the family.

“There’s a part of me that wants to stay inside all day, but then I remember that this kind of thing doesn’t happen in a small town like this,” Johnson said.