Brawl at Young Jeezy Concert

Jeezy was on stage rapping at the BB King Blues Club on Sunday ... when security asked some of the fans to move back from the stage. Sources at the scene tell TMZ ... a bunch of rowdy fans resisted ... and started talkin' smack to the security personnel.

Tensions grew ... until someone in the crowd fired a drink at the stage ... and that's when the place went nuts. Suddenly, everyone started fighting and throwing things ... including a mic stand.

Jeezy went on the loudspeaker and tried to calm everyone down ... but the crowd refused to yield ... so Jeezy and his entourage decided to exit through the back before someone got hurt.

Eventually, the violence died down. It's unclear if anyone suffered any major injuries in the ruckus.

Sources close to Jeezy tell us the rapper was "very upset" with the venue ... because he felt they should have done a better job controlling the crowd.