It happened Wednesday evening around 8 p.m. on Cary Court in the Bulls Head section.
The fire engulfed the entire building and the second floor collapsed. It also spread to a neighboring home also owned by Project Hospitality.
The home served as a transitional house to help the formerly homeless and has been in service there since 1990.
There were four apartments in the building with three people living in each one.
The 12 people have been relocated to another facility.
One person and one firefighter were injured in the fire. Their injuries are not life-threatening.