OAK PARK, Ill. — A first-floor business caught on fire and spread throughout a building in Oak Park early Friday morning.

Oak Park police responded to a fire on the first floor of a building in the 200 block of South Boulevard around 12:23 a.m. The fire spread from the first floor through the walls up to the second and third-floor residences.

According to the Oak Park police, the three-alarm fire caused smoke and water damage to 36 units in the area. There were no reported injuries except e a firefighter who was transported to Loyola University Medical Center and has been released to full duty.

The cause of the fire is still unknown at this time.