A 3-year-old boy has died after being found unconscious in a pool in Chandler, Arizona last week, officials said.

The Chandler Police Department has identified the boy as Trigg Kiser.

Officials said the incident happened just after 6:45 p.m. last Monday at a home near the intersection of Cooper and Chandler Heights Roads.

First responders said the boy was unconscious when they arrived, and they immediately began CPR.

It is unknown how long the boy was in the pool.

"Our thoughts and deepest condolences are with the child's family and loved ones during this unimaginable time," the Chandler Police Department said on Sunday. "The investigation into the circumstances surrounding this incident remain ongoing. This is still an open investigation. Out of respect for the family’s privacy, we will not be releasing additional details until the investigation is closed."

This story was originally published by the Scripps News Group in Phoenix.