Firefighters in Cicero were already dealing with a warehouse fire when an apartment building went up in flames.
The fire started at 1410 S. 50th Court and spread next door.
No injuries were reported.
Fire officials say they believe everyone inside the building is accounted for.
Flames were seen shooting out of the roof, but the fire got under control.
The Cicero Alternative School at 1874 S. 54th Avenue will not open this morning, after it was used as a warming center for firefighters and emergency response teams.
The cause of the fire is under investigation.