Large flames were already shooting from the roof when firefighters got to the scene around 2 a.m. near North Monticello Avenue and West Argyle Street in Chicago's Albany Park neighborhood.
CFD Battalion Chief David Dietz said the fire spread from a building under construction to buildings on both sides.
The fire was extinguished before 6 a.m. It forced several people out of their homes.
The cause of the fire remains under investigation.