Law enforcement sources tell us they got a call just after 6 AM Wednesday to Angus' home in Honolulu for a male who appeared to have drowned in a pool. We're told Angus was pronounced dead at the scene. At this time, there's no official cause of death.

Angus had spent Tuesday night with friends at his home, sharing a video of himself enjoying Hawaiian music with others.

Angus is the co-owner of John Paul Mitchell Systems, which was founded by his father back in 1980. He inherited his dad's stake in JPMS and its schools after his dad's death from pancreatic cancer in 1989.

Angus went to school for hairstyling, but once said most of what he learned came from his pops -- he worked in Hawaii for a number of years before opening the Angus Mitchell Salon in Beverly Hills in 2010.

Apart from traveling the world on behalf of JPMS, Angus also made a name for himself as an educator ... as well as a model and spokesman for MITCH -- a men's line under the JPMS brand.

He married Michelle Raab on the island back in 2010, and remarried twice ... once with Sian, whom he shares 8-year-old Dylan with, and his current wife, Mara.

Hairstyling was in Angus' blood from the beginning -- although he once admitted the path he ended up going down as a career was "one of the more difficult" ones he chose.

Angus took home multiple awards over the years -- including #1 Platform Artist by Be magazine, a whole day named after him in Beverly Hills, and 3 awards on behalf of the Alternative Hair Show, which raises money for leukemia research.

Angus was 53.