CHICAGO (STMW) — At least 12 people were displaced by an an extra-alarm fire that broke out in a Back of the Yards neighborhood apartment building on the South Side early Thursday.

Firefighters responded about 1:15 a.m. to the blaze at a two-story apartment building in the 4900 block of South Hoyne Avenue, according to Fire Media Affairs Director Larry Langford.

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Crews battled the two-alarm blaze from a defensive stance for nearly two hours before firefighters were able to get it under control, Langford said.

No one was injured in the fire, but between 12 and 18 people were displaced and were being assisted by the city’s Department of Human Services, according to Fire Media.

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Police said the building was an alcohol rehabilitation center.

The building appeared to have been illegally converted to have more living units than allowed under city building codes, Langford said.

Investigators determined that the fire started on the second floor of the building in one of the units, but the exact cause of the blaze was still under investigation early Thursday.

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(Source: Sun-Times Media Wire © Chicago Sun-Times 2014. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed.)