Several people have life-threatening injuries, Mr Neudigate told news channel WLWT-TV.
"We are in the middle of a very horrific situation that occurred at the nightclub with multiple victims. It's going to be a long night for our homicide units to investigate," he said.
Police Captain Kimberly Williams said the gunmen were still at large and the force did not have good descriptions of them. Witnesses had been reluctant to co-operate, she added.
"At this point it's unclear exactly what instigated the shooting," Capt Williams told reporters. "We believe that there were at least a couple of shooters involved."
