A fire displaced three families from an apartment house in Providence on Sunday afternoon. The American Red Cross said it was helping seven adults and one child after a fire broke out at 92 Lexington Ave. According to Providence fire officials, calls came in around 2:30 p.m for reports of a fire on the third floor. A battalion chief said there was extensive damage to the third floor and the attic. Providence fire officials said no injuries were reported. The department said the cause of the fire was under investigation.