The Norwalk fire department says working smoke detectors helped alert a family of an early morning fire Saturday.

Firefighters responded to a home on Boxwood Road just after 4 a.m.

Officials say the sleeping residents were alerted to the fire by properly installed and working smoke detectors.

A preliminary investigation suggests the fire spread from a fireplace or chimney that was used Friday evening.

Officials say while the fire spread into the home's structural framing, but firefighters were able to contain it just to the room it began in.

No one was displaced or injured.

The department says if smoke detectors had not been in use, the outcome of the fire could have been much worse, in terms of damages and possible fatalities.