Update, 7:15 p.m.: Still more photos added, including several of the firefighters' response from Lt. Shane Smith of the Darien Fire Department.

Update, 3:00 p.m.: More photos of the aftermath added to the box at right.

Update, 11:34 a.m.: Responders performed CPR on the owners' Jack Russell terrier for nearly fifteen minutes, according to one firefighter, but were unable to resuscitate the animal.

Update, 11:05 a.m.: "The house is pretty much a total loss" from fire, smoke, and heat damage, according to Fire Marshal Bob Buch.

Buch said that the blaze began around the family room at the rear of the house when "something rolled out or a sparked jumped out" from the fireplace.

The homeowners had gone to bed for the evening, but when one of them woke up smelling smoke, they opened the door to find the hallway filled with it.

The couple exited the house immediately, Buch said, but the husband reentered to see if he could locate the family dog. He was later transported to the hospital for smoke inhalation.

Buch said that he received an initial report of "heavy fire involvement" and arrived to find that the whole side of the house "was like a giant fireball."

Firefighters were able to extinguish the bulk of the blaze within about half an hour, but the age of the house meant that the flames spread quickly. It took another half hour or so to extinguish additional hotspots, Buch said.

In addition to the personnel originally reported, Ladder 30 from the Noroton Fire Department was also on the scene, accompanied by five firefighters.

Original article: A significant fire tore through the first floor of a house at 16 Sunset Road Wednesday night.

Both homeowners escaped without incident, but a dog died as a result of the blaze, according to a Darien Police sergeant on the scene.

The fire, initially reported around 10:34 p.m., was concentrated in a ground floor addition at the rear of the residence, police said. The cause remains under investigation.

A firefighter radioed around 11:15 p.m. that the blaze was under control but that crews were still working on "hotspots."

Firefighters could be seen placing a ladder on the front of the house and climbing onto the roof as white smoke poured out into the trees. The sound of breaking glass was also audible.

As responders worked, water gushed from a partially ruptured fire hose running along Mansfield Avenue, which was closed in both directions near the scene. 

A firefighter monitoring traffic said that the leak was affecting water pressure but that the hose delivered enough flow that it wouldn't have a significant impact on the response.

The Darien Fire Department, the Noroton Heights Fire Department, Post 53, Stamford EMS, and Darien Police were all on the scene.