Ex-NBA Star Earl Watson -- L.A. Mansion Robbed ... Renters Handcuffed, Home Ransacked

An L.A. mansion owned by former NBA player Earl Watson was robbed Monday night by at least 4 men in ski masks -- who handcuffed the occupants and ransacked the place.

While 35-year-old Watson owns the $4 million Encino home, he currently rents it out to a local elderly couple.

Officials say the men -- at least one of whom had a gun -- broke in through a back door and once inside, they handcuffed the couple and stole various items ... including cash.

Law enforcement sources tell us a maid was in the house -- who hid and called 911.