BREAKING: At least four hurt after ‘active shooter’ opens fire in Middleton

Four people are reportedly injured after a shooter opened fire outside Madison, Wisconsin, on Wednesday morning.

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.

The shooter is reportedly in critical condition.

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.