The Visalia Police Department says it happened just before 11 Thursday night at the Green Olive on Mineral King Avenue and Ben Maddox Way.
Police say the security guard tried to break up a fight inside the bar.
That's when one person pulled out a gun and fired several shots inside the building, striking the guard in the chest.
He was pronounced dead at the scene.
One other person was injured and taken to Kaweah Health Medical Center. They are expected to survive.
Police have not revealed any suspect information, but several witnesses were inside the bar at the time of the shooting.
Anyone with information is asked to contact authorities at 559-734-5302.