Twin toddlers who were found unresponsive by their mother in the family pool have passed away, according to a GoFundMe page set up by a family friend.

Kaydan died Saturday afternoon. Her brother Liam passed away Monday morning.

Family members said the 2-year-olds snuck out of the house on Acorn Court in Sterling Saturday morning. Their mother found them unresponsive in their pool.

“They all fell asleep together in bed, and she woke up to this tragedy,” a long-time friend wrote on the online donation website. “Brittany is an extremely dedicated and loving parent, and this incident is every parent's worst nightmare. She has not spent a day away from them since they were born, and has committed her entire existence to providing and caring for her babies.”

The twins were inseparable, the family said.

The Loudoun County Sheriff’s Office continues to investigate.