FDNY Lt. James McConville was on a run at about 10:30 a.m. Thursday when he noticed thick black smoke coming from a neighbor's home in the Silver Beach section of the Bronx.
McConville said he heard sounds coming from inside the house and immediately entered the building without protective gear, wearing only a T-shirt and shorts.
Inside, he found a man on the floor who was semi-conscious.
McConville dragged the man toward the front of the home, then returned inside to shut a door in an effort to help prevent the fire from spreading.
He then went back to remove the victim from the house.
The man had no pulse at that point, and McConville performed CPR and chest compressions.
After the lifesaving efforts, the man began breathing on his own.
A total of 21 units and 79 fire and EMS personnel responded to the scene.
Despite the rescue, McConville said he does not consider himself a hero.
"I didn't even think of it, I did it," McConville said.
McConville also emphasized the importance of closing doors during a fire to help slow the spread of flames.
The man inside the home suffered serious injuries. No one else was inside the home at the time.
The cause of the fire remains under investigation.