The occupants of five units in a Sanford apartment building at 7 Frost St. were displaced by a fire Sunday afternoon.

No one was hurt in the fire, which broke out in a third-floor apartment in the wooden structure at about 12:05 p.m., said Lt. Steven Ouellette of the Sanford Fire Department.

Ouellette said most of the tenants, including those in the third-floor apartment where the fire started, were home when a neighbor noticed smoke and shouted a warning to those inside the building.

Ouellette said the third-floor apartment was heavily damaged. Smoke and water damaged other units in the building, said Ouellette. He said about 24 firefighters fought the blaze. The scene was cleared at 3 p.m.

The cause of the fire is under investigation by the State Fire Marshal’s Office. It has not been ruled suspicious at this point, said Ouellette.

Ouellette said the American Red Cross is finding temporary housing for the displaced tenants.