Chicago woman discovers 'explosive materials' prompting evacuation

One person was detained after a woman reportedly found 'explosive materials' - however one report says the stuff was fake. But, was it? The report on NBC Chicago said:

An apartment building in Chicago’s Bronzeville neighborhood was evacuated after someone one "explosive material" inside a unit, sources told NBC Chicago. According to those sources, the building in the 500 block of East 33rd Street was evacuated after a worker found the materials inside an apartment on the sixth floor. An investigation revealed that the explosives were fake, as was a timing device found inside of the apartment. It is unclear what the origin of the fake items was, or why the tenant possessed the items.