From CBS Kansas City:
The shooter, Jahron Swift, was a person with a record who was not supposed to have a gun. After starting a fight with several people outside the club, he was denied entry into the building, got angry, went back to his car to get a gun, came back and started shooting wildly into the bar crowd.
He was killed by an armed security guard. Unfortunately, some young woman was killed by the idiot.
Not clear if he shot people outside the club or managed to barge into the building and then started shooting.