At least 8 injured in Chicago apartment building explosion

By Michael Hernandez

WASHINGTON (AA) - At least eight people were injured when an explosion tore through an apartment building, the Chicago Fire Department said Tuesday.

Officials initially said six were transported to local hospitals before revising the casualty count. At least three victims have been transported in serious to critical conditions.

"This is a confirmed explosion but source of explosion not known," the Chicago Fire Department said on Twitter, referring to the explosion as a "mass casualty" event.

Six transported to area hospitals are men while two victims are women, according to authorities.

Pictures posted to social media by the fire department show a residential building with nearly all of its top floor collapsed and many windows blown out.

The Bureau of Alcohol, Tobacco, Firearms and Explosives and the Chicago Police Department are on the scene.