The witness told the site that Brown lost his cool in the parking lot of the Westlake Recording Studios in L.A. after Ocean refused to shake his hand.

TMZ were told that Ocean simply laughed at the gesture ... and Brown became so angry that he cold-cocked Ocean and that led to the brawl.

Then the fight reportedly moved to the lobby of the studio which was destroyed in the brawl, "They managed to break almost everything in the room and scare all of the staff members working" says the witness.