A fire at an abandoned warehouse in Kensington, Philadelphia has claimed the lives of two Irish American firefighters.

Lt. Robert Neary, (60), and Daniel Sweeney, (25) were killed early Monday morning when a furniture store adjacent to the inferno collapsed and buried them under a pile of debris.

The blaze began at the vacant warehouse around 3.15am, as it quickly spread dozens of nearby homes were evacuated.

Fire commissioner Lloyd Ayers said it took two hours to recover the bodies of the two men. Two other firefighters were rescued from the site, and taken to hospital with non-life-threatening injuries.

"There was bricks, heavy timber, all kinds of other debris was on top of them. Actually the roof actually came in as well, so some of that materials had to cut, but a lot of it had to be moved by hand and it's a hard and tedious job. And then at times our members were using their listening equipment-- they would stop and listen to see if they heard any sounds so we would know what direction to direct the search," Ernest F. Hargett, Jr., Deputy Fire Commissioner told NBC News.

A 38-year-old veteran of the fire department, Lt Neary served in the Army reserve from 1972 to 1982 and also worked as a police officer before joining the fire service. He is survived by his wife, two sons and a daughter.

Timothy McShea, vice-president of the firefighters union described him as a great guy who knew the job very well.

“He’s like one of these old-school guys. They just have a second sense about them.”

McShea described 25-year-old Sweeney as a good young lad. He had become a firefighter in 2006, following in the footsteps of his father, retired Captain David Sweeney.

“Danny was a young, aggressive firefighter,” he said.

City officials claim the building had been cited several times for code violations. The law firm representing the owners of the vacant warehouse described the deaths as "an unspeakable tragedy."

Philadelphia Mayor Michael Nutter released this statement -- "These firefighters made the ultimate sacrifice for the people of Philadelphia. This is a tremendous loss for their families and the City of Philadelphia. My prayers go out to their families and to the Philadelphia Fire Department whose members have lost two of their brothers."

The cause of the blaze is yet to be established.

Lt. Robert Neary, (60), and Daniel Sweeney, (25)Philadelphia Fire Department