As TMZ first reported, Knight and Williams were involved in a huge fracas outside Eden nightclub ... and Suge nearly ran a few people over in his SUV as he sped out away.
We caught up with a guy named Joe last night ... who told us he was the guy Suge punched (you can watch it below in slow-mo). He claims Suge didn't like that he was recording the fight ... which didn't even matter, because Joe said his video was terrible anyway.
As for how it all began, Joe says that Katt called some guy "a Mexican" and when the guy confronted him on it, Katt decked him. Joe says Katt then tried to back away and apologize to defuse the situation ... but clearly that didn't work.
Joe also says he was the reason Suge sped off ... because Joe says he was punching Suge's window right before he peeled out.
Joe ended our conversation by calling Suge "a bitch" ... so it was nice knowing you, Joe.
*** WARNING: VIDEO CONTAINS LOTS AND LOTS OF PROFANITY