The fire broke out in a living-room couch in Apartment 67 at 1736 Lafayette Ave. It was reported at 11:30 p.m.
Firefighters confined the fire damage to three apartments, but the Red Cross was called to assist residents from seven apartments. One resident was hospitalized after suffering burns to her hand.
The blaze caused an estimated $60,000 damage.
A fire investigator fell and suffered a puncture wound to the leg. He was taken to Niagara Falls Memorial Medical Center for a tetanus shot.