A city Bravest was killed in a ferocious Brooklyn house blaze Sunday afternoon — two years after he gave a moving eulogy for a fellow firefighter who also died in the line of duty.

The inferno at 10826 Avenue N in Canarsie turned deadly when flames suddenly swept through the second floor — sending smoke-eaters leaping from windows and part of the structure caving in on itself, fire officials said.

The dead Bravest, Timothy Klein — the 31-year-old son of a retired fireman — apparently became separated from his comrades and was fatally injured in the structural collapse, according authorities and sources.

Eight other firefighters also were injured, either in the collapse or from burns, officials said.

“Everything seemed to be going routine when suddenly the entire second floor became engulfed in flames,” said Acting Chief of Department John Hodgens at a press briefing at Brookdale Hospital in Brooklyn on Sunday evening.

“Three other members that were with [Klein] were able to escape by jumping out windows and getting out ladders in other areas of the building.

“Our members worked feverishly, very hard under very difficult conditions, to try to reach [Klein],’’ Hodgens said. “Unfortunately, they were not able to get to him in time, and he succumbed to his injuries.

“Timothy lost his life doing his job that was asked him every day.”

Mayor Eric Adams added, “It gives us great pain and sorrow to announce that New York City has lost one of its bravest, Timothy Klein, 6 1/2 years as a firefighter, 31-years-old, coming from a rich tradition of dad and other relatives who are firefighters.

“New York has lost one of its Bravest.”

Hundreds of cops and firefighters lined up outside the medical examiner’s office on Sunday night to salute Klein as his body arrived.

Klein, who was assigned to Ladder Co. 170, had given the eulogy for fellow firefighter Steven Pollard in 2019, after Pollard was killed at the scene of a car crash on the Belt Parkway when he fell through a gap in the roadway.

“Steven Pollard died not thinking of himself but trying to help others,’’ Klein said at the time of his fallen brother who worked out of the same firehouse. “We lost a true hero that night. It breaks my heart to know that the days working alongside you are over. … You will never be forgotten.’’

On Sunday, it was Klein — a six-year department veteran — who was rushed to Brookdale University Hospital Medical Center, where he was pronounced dead, sources and officials said.

Klein grew up in Breezy Point, Queens, and lived in Rockaway, sources said. He is survived by his father, retired FDNY Firefighter Patrick Klein, his mother Diane, and his three sisters, according to officials.

An FDNY rep said firefighters were dispatched to the two-story home at 1:39 p.m., with more than 100 Bravest working the scene as the blaze was quickly elevated to a third alarm shortly after 2 p.m.

Klein was assigned to the nozzle team that was extinguishing the flames when the unimaginable happened, officials said.

“The incident commander identified deteriorating conditions and ordered all members out of the building,” said Acting Fire Commissioner Laura Kavanagh at the press briefing. “As they were doing so, there was a partial collapse of the ceiling. Four members were caught in that collapse — three [got] out and are stable at local hospitals at this time.”

Neighborhood resident Clara McKenley, 24, said the blaze was “the scariest thing I’ve ever seen.”

“The flames were massive, and there was so much smoke,” she said. “Everybody was running back inside their houses to get away from it.

“It just kept burning and burning,” McKenley said. “You felt like the wind was going to blow the flames from house to house.”

Neo Malcolm, 19, who lives a block away, said his grandfather initially thought a neighbor was barbecuing in the area.

“The flames were so high, like 10-feet high, and the smoke was at least 150 feet in the air,” he said.

“A while later, they started rushing stretchers,” Malcolm said. “I definitely saw one with a firefighter lying on it, and there were 12 guys running along with it, but I couldn’t tell if he was the one who died.”

Adams said the five hurt firefighters suffered non-life-threatening injuries. A resident at the address was still unaccounted for, he said.

A civilian who was injured was treated at the scene and refused further medical attention, the FDNY said.

The injured firefighters were taken to Staten Island University Hospital after suffering burns, sources said.

Andrew Ansbro, president of the FDNY Firefighters Association, said in a statement, “There are no words that aptly describe the loss of a fellow Firefighter in your company and this department, and the Klein family is now living the worst nightmare of every person who has ever sworn the sacred oath to the FDNY.”

FDNY Lt. James McCarthy, president of the FDNY Fire Officers Association, added that Klein’s “sacrifice embodies the ultimate heroism, laying down his life for others.”

Klein is the 1,157th member of the FDNY to die in the line of duty, fire officials said.

The last city firefighter to die in the line of duty was 33-year-old Jesse Gerhard in February.

Additional reporting by Reuven Fenton