The child, believed to be about 1 year old, was left in a room sleeping by himself as his mother was working out in the Zumba studio, witnesses said.
He apparently fell into a mop bucket, witnesses said.
Paramedics were called to the facility in the 12000 block of Saticoy Street in North Hollywood at 11:18 a.m. on a report of a non-responsive boy. The child was transported to a hospital and pronounced dead.
Per the agency's protocol in child death cases, the Los Angeles Police Department's Abused Child Unit is investigating the circumstances.
#BREAKING: @LAPDHQ investigating the drowning of a 1-year-old in North Hollywood. Witness says mom was in a Zumba class when her baby in the next room fell into a mop bucket and died. @ABC7 pic.twitter.com/mEVKf1fdeB— Veronica Miracle (@ABC7Veronica) November 30, 2017