Most, if not all, of the building's tenants were asleep when the fire broke out.
Jeff and Chris Harper, 27, were watching wrestling on television in Chris' Broadway basement apartment nearby when they heard windows break and a crackling sound, Jeff Harper said.
Jeff Harper, 24, said he saw flames shooting out of the brick building and quickly grabbed his shoes and his cellular phone and called 911 as he ran to wake residents.
"None of the smoke alarms went off. If it wasn't for this guy and his brother everyone would probably be dead right now," said tenant Connie Granda, 43.
"They were pounding and yelling, 'Get out,'" Granda said.
Maria Martz said the Harper brothers awoke her son, who then got her and her daughter up.
"If it wasn't for them, I don't think any of us would be around," said Martz, who has lived in the building for 16 years.
"Angels and heroes in my book," said Robert Thomas, 32, who lives in the southwest third-floor apartment.
Thomas and other tenants also credited the fire department for its quick response.
"It wasn't long. They had everything under control," said Betty Jordan, 65, who lives on the second floor. The fire was out by 4:19 a.m.
Several tenants said smoke and/or flames started seeping into their apartments just as the Harpers warned them to get out.
Jeff Harper said he kicked in one woman's door just as she was opening it and knocked her down. When she turned around he said he saw flames shooting out of the wall.
Harper said he had experience putting out fires as a Navy yeoman, but he didn't try to fight this one.
"The heat itself, when I got to the third floor, was just unreal," Harper said.
The smell of smoke lingered outside the building Tuesday afternoon when Jordan returned to her apartment to pick up some food and belongings.
Jordan said firefighters had to pull her sofa out to save her cat, Baby, who was expected to recover from smoke inhalation after being given oxygen at the Cumberland Valley Veterinary Clinic.
The apartment where the fire originated was gutted while the other third-floor apartments were heavily damaged by heat and smoke, fire officials said.
Apartments on the first and second floors had lots of water damage, said Fire Capt. Kyd Dieterich.
Next-door neighbor Kelly Zimmerman, who was washing soot off her front porch Tuesday afternoon, said the fire caused some damage to the roof of her duplex.
Horn said firefighters first tried to get to the fire by going up the front steps, but had to come back down and go around to the back when they realized the rear of the building was an addition and wasn't accessible from the front.
Tenants hung out in the driveway behind the building or in their cars Tuesday morning while taking turns being interviewed by Red Cross officials.
Seven tenants were provided shelter through the Red Cross with seven others were staying with family or friends, Kline said. All of the tenants were not accounted for since not everyone was home during the fire, she said.
Fire officials weren't certain whether the building was insured. It is owned by John Benisek, who could not be reached for comment.
A firefighter was treated at Washington County Hospital and released after stepping on a nail, fire officials said.
First Hose, Antietam, Junior, Western Enterprise, South End and Pioneer Hook and Ladder were assisted by Long Meadow and Community Rescue Service.
Staff Writer Marlo Barnhart contributed to this story.