Last night, things turned ugly between Frank Ocean and Chris Brown at a West Hollywood recording studio.

The R&B stars have shared arguments in the past, but called a truce on Twitter back in 2011. However, both men along with several friends were reportedly involved in a physical altercation at a Westlake Studio on Sunday evening (Jan. 27). TMZ claims Frank and Chris were both working at the studio when Brown attempted to leave but was blocked by Ocean and his crew.

"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." -TMZ/em>

According to Ocean's Twitter messages, there may be a different story. After the alleged incident, Frank tweeted: "got jumped by chris and a couple guys. lol. i only wish everest was there."

"cut my finger now I can't play w two hands at the grammys."

Police are actively investigating the incident and witnesses say Chris Brown assaulted someone in the melee. 6 men were reportedly involved in the brawl.

Stay tuned for more on this developing story.