A small explosion sparked a fire at the Rowney Terrace Apartments on South Bancroft Street, late Saturday night.
IFD crews arrived around 11 p.m. to find heavy smoke billowing from one unit. No one was home there and there were no injuries, but four apartments in all had to be evacuated because of structural damage.
Victims Assistance was helping the displaced families find some place to stay.
IFD is working to determine the cause of the explosion.