Fire broke out just after 9:00 p.m. in a 3-story house on the 1700 block of West Girard Avenue.
The fire was brought under control in less than 25 minutes.
A 60-year-old woman was taken to Hahnemann Medical Center for smoke inhalation.
Police say the woman was seriously injured,
According to officials, the fire was deliberately set and a suspect is in custody.