The blaze broke out in Middlesex County around 4:30 a.m., Thursday, Sept. 1 on Pine. St., in Middletown.
According to Middletown Fire Chief Jay Woron, firefighters arrived on the scene within four minutes and encountered heavy fire in the duplex structure with fire and the first floor and quickly moved to the second floor and the attic.
Firefighters on the scene were informed that two people were unaccounted for and began a search of the building, Woron said.
Teams quickly found one person on the second floor and evacuated them. The second person, a man, was found trapped in the first-floor apartment with heavy burns, Woron said.
He was removed and received medical attention from emergency services for more than 45 minutes but the man eventually died on the scene, the chief said.
Four adults and three pets were evacuated from safety and are being assisted with temporary housing by the American Red Cross, Woron said.
The structure is unhabitual, he added.
Firefighters were able to put out the fire in about 30 minutes, Woron said.
The fire is currently under investigation by the Middletown Fire Marshal’s office and the State Fire Marshal's Office due to the fatality.
The name of the man killed was not released.
Click here to follow Daily Voice Shelton and receive free news updates.