What we know:

Crews responded to the blaze around 6 a.m. in the 600 block of North Saint Louis Avenue, according to the Chicago Fire Department. 

Upon arrival, firefighters found the rear porches of a building at 636 N. Saint Louis Ave., burning. The fire then spread to the rear and interior of the adjacent building at 638 N. Saint Louis Ave.

A still and box alarm was issued due to the extent of the fire, which affected both apartment buildings. The fire was struck out around 7:10 a.m. Fire officials confirmed that the blaze was under control and that primary searches of both buildings were negative.

No injuries were reported and all occupants appeared to be safe. However, there will be resident displacements as a result of the damage, fire officials said. 

The cause of the fire remains under investigation.