CHICAGO (CBS) — Firefighters rescued two children Tuesday morning while responding to a fire at a two-story apartment building in southwest suburban Tinley Park.

Tinley Park Fire Chief Forest Reeder said firefighters responded to the fire late Tuesday morning on the first floor of a four-unit apartment building on the 6500 block of West 173rd Place.

Firefighters found two children on the second floor, and got them out through a bedroom window using ladders, according to Reeder.

Medics treated the children at the scene.

Orland Park and Oak Forest firefighters helped extinguish the fire, which left the building uninhabitable, displacing four families.

The cause of the fire is under investigation.