NORWICH, Conn. -- Norwich firefighters battled a blaze at a three-story apartment building fire that broke out at 2:30 a.m. Sunday in the 200 block of Central Avenue in Norwich, Norwich Fire Department Chief Kenneth Scandariato said. The first floor is a convenience store called Sunshine Farms.

There are eight apartments in the building, seven of which have tenants. At least 21 people have been displaced and three people have been injured, police said.

One elderly woman suffered critical burns and was flown by medical helicopter to Bridgeport Hospital after initially being taken to W.W. Backus Hospital, police said. The other two people injured were Norwich firefighters who were attempting a third-floor rescue. One firefighter slipped on a ladder because it was icy. Both suffered minor injuries and are expected to be fine. Both were taken to Backus for evaluation.

Fire officials said the building, built in 1896, is a total loss and will have to be razed. Department officials also mentioned it was a difficult fire to fight because there are voids in the building and once the fire gets into the voids, it is difficult to stop it.

When firefighters arrived, the first two floors were burning, as well as the front corner of the building. The first 12 firefighters to arrive were first concerned with rescuing residents.

The Charter Oak chapter of the American Red Cross went to the fire scene and is assisting those who lived in the building.

Shortly after the fire broke out, much of the city suffered a brief power outage, but all power has been restored. The outage triggered more fire and burglar alarms, and 911 dispatchers received numerous calls. Police said they wanted to remind residents that 911 is for emergencies, not routine inquiries.