GEORGETOWN -- On any given weekend, people flock to Lake Georgetown to enjoy a day on the water. Kayla Reynolds and her family are regulars there, but now it will be a long time before she goes back.

RELATED: Foster home investigated following sibling drowning

"I'm just a little traumatized by it," Reynolds said.

Just before 5:00 p.m. on Sunday Reynolds and her kids had just gotten out of the water when she noticed a young boy a few feet away.

"I saw a little boy pick a girl up out of the water and he was holding her and her head was kind of flopping around," described Reynolds. "As I looked closer, her eyes were open and her lips were white and she wasn't moving...He said that he thought he stepped on a fish or something and bent down to pick it up and it was the girl."

A nurse at the beach started performing CPR on the 6-year-old girl while Reynolds called 911. About 15 minutes later, she said a family friend came over to them.

"A man ran up and said that he knew her, and it wasn't her dad or anything but he knew her, and where was the little boy. There was a little boy missing," Reynolds said.

She says the man got into the water and about five minutes later pulled the 4-year-old boy's body out. The siblings were flown to Dell Children's Hospital where they were pronounced dead.

Georgetown Police say the boy who found the girl was a 12-year-old family friend and the siblings were playing a game of who could hold their breath the longest.

Reynolds says there are free life jackets around the lake but the kids weren't wearing any and there wasn't an adult with them.

"There was nobody. There was nobody for the first five or ten minutes they were doing CPR on the girl. Everybody was looking around asking where her parents were," said Reynolds.

"Child safety is our number one concern. This is unacceptable," said Julie Moody, Spokesperson for the Department of Family and Protective Services.

According to a DFPS spokesperson, the children's foster parents were investigated about two months ago for claims of physical abuse, but investigators found no harm. Now the department is investigating the death of the children.

"Even if it turns out after the investigation that this turns out to be an accidental drowning, it's still unacceptable," added Moody.

The children who died were from Waco and were placed in the foster parents home in Cedar Park in August 2013. They have two siblings, a one-year-old and 22-month-old, who also lived in the same home. Those children have been removed and the foster home is closed.

The children were placed in the home by Austin-based Providence Kids child-placing agency. That agency has been suspended pending the outcome of the DFPS investigation of the incident. Providence Kids has 29 foster children in eight homes in Williamson, Travis, Bell, Lee and Hays counties. As a precautionary measure, Child Protective Services will visit each child in the foster homes individually.

Providence Kids has also been directed to immediately provide all foster parents and other providers with water and heat-related safety information.

Georgetown police say the drownings are accidental and they don't expect to file charges, but the investigation is still open and officers will take their findings to the District Attorney before closing the case.