CHICAGO (CBS) — Two men were injured overnight a fire in the Humboldt Park neighborhood, which has been blamed on misplaced smoking materials.

Firefighters extinguished the blaze at the apartment building at 1152 N. Christiana Ave. about 12:20 a.m., according to Fire Media Affairs.

Investigators say the fire broke out just before midnight on the fourth floor. Flames and smoke were contained to two apartments, but the entire building, which contained between 40 and 50 units, had to be evacuated.

Two male victims were taken to area hospitals, one in serious-to-critical condition to the Saint Mary campus of Saints Mary and Elizabeth Medical Center, and the other in fair-to-serious condition to Norwegian-American Hospital, according to Fire Media Affairs.

One man, 51, suffered more serious smoke inhalation injuries than initially thought and was transferred to Stroger of Cook County where he is now in serious condition, a Harrison District lieutenant said. The other man, a 52-year-old, had been upgraded to good condition early Wednesday.

Careless use of smoking materials caused the accidental fire, the lieutenant said.

The Sun-Times Media Wire contributed to this report.

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