Someone fired a gun inside Visions Nightclub on East Washington Avenue in Madison around 2 a.m. Sunday morning.
Four people were shot. The injured -- a male, 46; a male, 42; a male, 35; and a female, 31 -- were all transported to a hospital for treatment. The extent of their injuries was not known as of 5 a.m. Sunday.
Police were called to the scene for a report of a large fight.
Investigator say there is no danger to the public.