According to TMZ:
Chris Brown was involved in an all-out brawl with Frank Ocean Sunday night, and sources connected with Chris insist Ocean started it.
Chris was at Westlake Studio in the L.A. area listening to one of the artists he represents. The sources say as Chris went to leave, Frank Ocean and his crew blocked Chris from leaving. The sources say Frank said, “This is my studio, this is my parking spot.”
We’re told Chris went to shake Frank’s hand … and that’s when one of Frank’s people attacked Chris. Sources connected with Chris say one of Chris’ friends jumped in front and hit Frank’s friend.
Sources connected with Chris say Frank then came at Chris … Chris pushed him away and they started brawling.
The police were called and are on scene now.