A 19-year-old man died after an unauthorized Memorial Day pool party at an northwest Atlanta apartment complex, officials said.

The incident happened just before 8 p.m. Monday at The 500 apartments on Northside Circle, Atlanta police spokeswoman Officer Stephanie Brown told Channel 2 Action News. Officers were sent to the pool after receiving complaints of a large party there.

“While on scene, officers were notified of a 19-year-old male who appears to have drowned at the location,” Brown said.’

Witnesses told Channel 2 the man was in the water for as long as 20 minutes before someone noticed him. Officials conducted CPR before taking him to a hospital.

The Fulton County Medical Examiner’s Office identified the man as Shomari Billings.

His mother, Shelley Billings, spoke to Channel 2 at a vigil held for her son Tuesday night, and she’s searching for answers.

“I don’t know what hurts worse — me not having my child or me not knowing exactly what happened,” she said. “I need to know if someone pushed him in the pool.”

A GoFundMe page was set up for his funeral costs, and it had raised over $900 as of Tuesday night.

A statement from The 500 said the party was an unauthorized event and broke several rules, including the use of alcohol in the pool area.

“Any residents responsible for planning or promoting this event have violated the terms of their lease and will have their lease terminated,” the apartment complex told Channel 2.

Authorities said the partygoers left before the event was shut down.

An investigation is ongoing.