CNN reports that an unidentified gunman is believed to have opened fire in an office building in the Middleton, a Madison suburb west of Milwaukee.
BREAKING: Police responding to report of an active shooter in a suburb of Madison, Wisconsin. https://t.co/AWk4OAvBCG
— The Associated Press (@AP) September 19, 2018
A motive for the mass shooting is not yet known. This is a developing story, and all information is preliminary.
CrimeOnline will provide further updates once more information is available.