An FDNY firefighter fell through a window and down a 40-foot shaft during a multiple alarm fire in Manhattan.Sam Costanza for the New York Daily News/TNSAn FDNY firefighter suffered serious injuries after falling 40-feet down a building shaft while battling a fire in Harlem on Friday.    

A firefighter suffered serious injuries, but miraculously survived, after falling 40-feet down a building shaft while battling a five-alarm blaze in Harlem on Friday.

The fire started inside a second-floor apartment at the six-story apartment building on W. 145th St. near Broadway around 2:45 p.m., according to the FDNY.

More than 200 firefighters and paramedics rushed to engage the fire, which rose to the building’s top floor before blowing out the top-floor windows, according to FDNY Chief of Operations Kevin Woods.

“These old buildings have many, many voids,” Woods said at a press conference at the scene. “The fire gets into these voids and when it got into the sixth floor it actually started blowing out of the top floor windows.”

Bobby Dillird witnessed the fire’s spread from his apartment across the street, saying the blaze appeared to die before suddenly reigniting.

“It started on the second floor. It blew out the windows. It died down but then it flared up again. It went from the 3rd to the 4th floor. The firefighters looked back and it was burning like it had just started,” Dillird told the Daily News. “Then it went up through the other floors and blew out the roof.” 

One smoke eater was handling a hose line as he backed down a flight of stairs and smashed into a fourth-floor window on the building’s east wing, FDNY Fire Commsioner Robert Tucker said.

The window gave way and the firefighter plummeted 40-feet to the ground below, said Tucker.

Members of one of the FDNY’s elite fire rescue companies rushed to aid the injured firefighter, who was taken to Harlem Hospital in a serious but stable condition.

Mayor Adams gave a brief update on the injured firefighter’s status outside the scorched building and also visited him at the hospital.

“He was awake and responsive, you know… of good spirits,” said Adams. “Thank God he was able to leave this scene. Someone was just telling me, as he was leaving the scene, he gave a thumbs up signal to let folks know that. He’s in serious condition, and the doctors are going to do what they do best.” 

Five building residents and three other firefighters were treated for minor injuries.

Displaced tenants were directed to a makeshift shelter at the PS 153 Adam Clayton Powell School on nearby Amsterdam Ave.

One survivor described how the fire spread to the fourth-floor apartment where he lives with his 62-year-old mother, destroying their unit and leaving them destitute.

“My mother was in a panic. All of a sudden the fire rolled up from the second all the way to the sixth floor. It went up very quickly,” said 28-year-old Derrick Meran. “I’m not sure what we’re going to do now. Basically our home is destroyed.”

The cause of the fire remains under investigation.