An elderly man died as fire raced through a 2 1/2 -story home at 255 Dearborn St. in Black Rock about 9 p.m. Friday.
Neighbors, meanwhile, were credited with rescuing a woman from her first-floor quarters, fire officials said.
Firefighters arriving on scene saw flames shooting from the second floor of the building, according to Battalion Chief Anthony Hynes.
Five young neighbors ranging in age from 14 to 20 broke down a first-floor door and led a woman in her 70s, as well as some pets, to safety.
The man, described as the woman's estranged husband, who lived on the second floor, died in the fire, fire officials said. The victims were not identified.
David Castle, 14, of Thompson Street, a seventh-grader at West Hertel Academy, said he was with friends when a neighbor pointed to "smoke or fog," and they noticed the house was on fire.
"We started pounding on the lady's windows and then we kicked down the door," David said. "We put her out on the porch, but she tried going back in there to get her cats."
David was helped by Donald Plant, 14, of Dearborn Street; Carl Nye, 20, of Austin Street; Steve Davison, 18, of Thompson Street; and Anthony Gatti, 16, of Austin Street.
"By the time we got in the stairway, the upstairs was already engulfed," Nye said.
Added David: "The fire already started up. My heart was pounding."
The man's body was recovered toward the front of his second-floor rooms, where the blaze originated, firefighters said. He was declared dead at the scene.
The woman was not injured, officials said.
The fire consumed the entire second floor and attic. Fire officials estimated damage at $80,000.
Fire Division Chief Thomas Ashe said the cause of the fire does not appear to be suspicious. However, the case remains under investigation.
Fire officials remained at the scene past midnight.