Cheryl Satores, 50, was charged with the Thursday morning fire at the Washington Place Condominiums in Washington Township.
Police say Satores, who lived in the same complex, was charged with second-degree arson.
The fire was reported around 5:45 a.m. and all residents were able to escape safely.
Investigators say an inspection of Satores' unit by an arson detection K-9 uncovered accelerants in a sunroom.
Satores was arrested and bail was set at $50,000 cash.
Her motive for setting the fire was not yet known.