With the water from their hoses cut short and the fire consuming the walls and doors and air around them, six city firefighters had to jump from the top floor of a burning apartment building in the Bronx early yesterday morning.

Two of the firefighters, Lieutenant Curtis Meyran, 46, of Battalion 26, and Firefighter John Bellew, 37, of Ladder 27, were killed after their estimated 50-foot fall into an alley behind the building at 236 E. 178th St. The other four firefighters – Joseph DiBernado and Jeffrey Cool from Rescue Company 3, and Eugene Stolowski and Brendan Cawley, of Ladder 27 – were in critical condition last night at St. Barnabas Hospital, officials said.

Another firefighter was killed yesterday in a fire at Brooklyn. In attempts to rescue any trapped occupants at 577 Jerome St. in East New York, fire department officials said, Richard Scalfani, 37, of Ladder 103, became separated from his colleagues and was found minutes later, unconscious and suffering from respiratory arrest, in the basement of the burning building, officials said.

One of the critically injured firefighters in the Bronx, Brendan Cawley, lost his brother, Michael Cawley, a firefighter with Ladder 136 in Queens, at the World Trade Center in 2001. The New York Fire Department lost 343 members in the September 11 attacks.

“When I was a kid, he used to tell me that I had to be a firefighter,” Brendan Cawley told Newsday in an article written after those attacks. “When I asked him why, he told me it was because being a firefighter was the greatest job in the world.”

In a Bronx press conference yesterday, Mayor Bloomberg said: “The Cawleys have given a lot for this great city, and we pray that God doesn’t take another member of this wonderful family.” The commissioner of the fire department, Nicholas Scoppetta, said the firefighters in the Bronx were trying to save people in the most dangerous location: the floor above a fire.

“It is just another terrible example of what firefighters do every day,” Mr. Scoppetta said. “They put their lives on the line, and unfortunately two of our members paid the ultimate price.”

Meyran, a father of three from Melville, Long Island, and 15-year veteran of the fire department, had been decorated for bravery after having previously pulled two young girls from a fire in Brooklyn, his brother, Glenn Meyran, said yesterday. “He liked the job, but he knew the risks and I knew the risks.”

Bellew, of Pearl River, in Rockland County, was a father of four, family members said; his youngest boy, Kieran, was born only last August. Bellew’s mother, Marguerite Bellew, described her son yesterday as active and generous, coaching a soccer team with his wife, Eileen, and taking his kids to the YMCA.

“He loved the fire department,” Ms. Bellew said yesterday. “He was a wonderful person and a wonderful father.”

The causes of both fires are still under investigation, but fire department officials said they believe the source in the Bronx fire could be an electrical cord. After a preliminary investigation, officials said the cord had been resting next to a mattress on the third floor of the building. Some time before 8 a.m., the cord is believed to have short-circuited, sending sparks onto the mattress, which ultimately caught on fire.

In total, 150 firefighters, many with snow on their boots and frost on their faces, had arrived on the scene by 10 a.m., officials said.

The injured firefighters were searching the top floor of the building after hearing reports that tenants were upstairs. They became trapped when the water pressure on their hoses was cut off, the chief of the fire department, Peter Hayden, said. Officials were looking into the cause of the failed water supply. A rescue attempt was made but proved unsuccessful.

Faced with a burning building and no means of escape, all six firefighters chose to break through the windows and escape the suffocating smoke and heat.

“It is a choice no human being and no firefighter ever wants to face,” Captain Peter Gorman, president of the Uniformed Fire Officers Association, said.