North Sea Fire Department Chief Brian Robinson said that there were no injuries suffered by occupants of the house at 195 Little Fresh Pond Road or to firefighters who responded to the scene.
The fire appeared to have started in the kitchen area of a downstairs apartment and spread to the main portion of the house above. The house suffered substantial internal damage but firefighters were able to extinguish it before it spread to the outer portions of the structure.
Chief Robinson said that the house was occupied when the fire broke out but that all residents were able to get out of the house unharmed.
The exact cause of the fire is under investigation by Southampton Town Fire Marshals but police said the cause did not appear suspicious.
Three fire departments and the Southampton Volunteer Ambulance Corps have been called to a fire on Little Fresh Pond Road on Thursday evening.
The North Sea, Southampton and Sag Harbor fire department were all on the scene of the fire, which was called in about 4:30 p.m.
Southampton Town Police said the fire was called in by one of the occupants of the house and that there was a report from the scene of a possible medical emergency, but police could not confirm whether there had been anyone injured or in need of medical attention at the scene.