Law enforcement sources tell TMZ, Flav -- real name William Drayton Jr. -- allegedly got into a heated verbal argument with a teenager in his house, as well as his fiancee. His fiancee then called 911. It's unclear if the teenager is Flavor's child.

According to law enforcement sources, Flav allegedly threatened one person with a knife during the argument, and battered the other -- it's unclear which person he threatened, and which he physically attacked.

Flav was arrested around 3am and booked on two charges -- felony assault with a deadly weapon and misdemeanor domestic violence (battery).