A California toddler is dead and her 17-month-old twin sister is in critical condition after they reportedly climbed out of a living room window and plunged into a pool as their parents slept.

The girl’s family told KTLA that Maya and Makayla Edwards suffered traumatic brain injuries on April 29 when they managed to push out a screen window and access the pool, which was not fenced in.

Erika Alvarado said she and the child’s father, Jeremiah Edwards, had dozed off for a few minutes while the girl’s played in the living room. When Alvarado awoke, she said the doors were locked and the twins were nowhere to be found.

Alvarado recalled running to the backyard and finding the two toddlers in the pool. Both parents hopped in to save the girls. Alvarado told KTLA that they performed CPR but neither girl had a pulse.

The mother revealed that both girls suffered extensive brain damage and were both medically sedated and moved to the pediatric intensive care unit.

The news station reported Makayla woke up on May 12—the same day Maya died after being taken off life support. Her father said Maya’s heart was donated to another baby who needed a transplant.

“That twin connection that people tell us about—she’s thriving off of that,” Alvarado said of her surviving child. “She hopefully knows that her sister is watching over her.”

[Featured image: Maya and Makayla Edwards/GoFundMe]