A family mourns the death of a 4-year old, after bystanders found the unconscious boy in a north Austin apartment complex pool Thursday.

The Travis County Sheriff's office said the investigation reveals that the adults did not notice Xander Drayton jump in the water.

They said it's not known how long he was underwater before being pulled out of the pool.

Bystanders, who found Drayton and administered CPR, called emergency crews to the apartment complex, an EMS spokesperson said.

Rescue workers called a Star Flight helicopter to fly the child to the hospital, but rescuers then declared the child dead.

"It's heartbreaking," Roger Wade of the sheriff's office said. "It can't be as bad as the family is feeling now, but it is heartbreaking for first responders to come upon a scene where a child has been injured or has died."

The Travis County Sheriff's Office was called to investigate.

The incident happened at about 3 p.m. Thursday at the 2800 block of Wells Branch Parkway between Double File Trail and Single Trace.

Drayton was from Pflugerville and was visiting family at the apartment complex.