Firefighters say they have found three young children dead in an apartment building that caught fire on Chicago's southeast side.

Fire Department spokeswoman Eve Rodriguez says the bodies of a 7-month-old boy, a 2-year-old boy and a 3-year-old girl were found Wednesday on the top floor of a three-story building. Officials were investigating possible causes, including the misuse of a space heater.

A 4-year-old boy found on the second floor was taken to a hospital in good condition.

Rodriguez says the mother of all four children was outside the building when firefighters arrived. Neighbors say they heard the children screaming but couldn't reach them because of the heavy smoke.

Authorities say no working smoke detectors were found at the residence.

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