Cooking left on the stove is being blamed for the fire, which left a third-floor apartment and one below it uninhabitable, Beavercreek Twp. Fire Lt. Matt Clark said.
The sprinkler system kept the fire in check and extinguished it quickly.
Lt. Clark estimated the damage to the apartments and their contents at $20,000.
The person taken to a hospital suffered from smoke inhalation, he said.
Crews were dispatched to the Lofts, 2621 Hibiscus Way, just after 11 p.m. on the report of a structure fire, according to Beavercreek police and fire dispatch.