A 21-year-old man was found dead in Demi Moore's swimming pool in L.A. on Sunday.

Police are ruling it an accidental drowning, and Demi wasn't there when it happened.  Her daughters Scout and Tallulah have been throwing a bunch of pool parties at her house this summer, but they weren't there either.

The person who house-sits for her had at least five people over on Saturday night.  One of them called 911 around five o'clock Sunday morning after they found him.  Some reports say he'd been floating on a raft, and might have fallen asleep on it.  TMZ says he didn't know how to swim, and might have just slipped and fallen in. He also may have been drinking, but it's not clear how much.  As of last night, police were still waiting on the toxicology report.

The house where it happened is the one Demi bought with Ashton Kutcher in 2003, about two years before they got married.

Photo By: Jason Merritt/ Getty Images