By Marlena Baldacci and Chuck Johnston, CNN
Four people were wounded Wednesday morning when a gunman opened fire in a small Wisconsin city, police said.
The suspect was also injured and is in critical condition, city officials said.
The motive for the shooting, which appears to have unfolded in an office building, is not yet known.
Authorities are now in the process of clearing the building and the surrounding area.
About 50 police cars plus the FBI responded to the scene in the 1800 block of Deming Way, Keely Arthur of CNN affiliate WISC reported.
The regional office of the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) said it is also responding to the scene.
Middleton, a suburb of the state capital Madison, is a city of about 17,000 residents.
“My heart goes out to the people involved in the shooting,” Middleton Mayor Gurdip Brar said. “You never would think this type of thing would happen in your city. Really, so sad that this happened here.”