The blaze broke out on the 16000 block of Bliss Lane at about 2 a.m. Friday.
Authorities said the fire left two units burned and another two with water and smoke damage.
In total, 21 people have been displaced, including four children.
One person was taken to the hospital suffering from smoke inhalation. The blaze was knocked down in about 30 minutes.
The cause of the fire was under investigation.
City News Service contributed to this report.
