One of the two NYPD officers critically injured during a high-rise fire in Coney Island on Sunday has died, the NYPD said. Housing police Officer Dennis Guerra, a father of four, died at 6:50 a.m. Wednesday at Montefiore Medical Center in the Bronx, police said.

Guerra, 38, and fellow housing police Officer Rosa Rodriguez, 36, both from Queens, were critically injured when they were overcome by dense smoke and toxic fumes from a mattress fire on the 13th floor of an 18-story high-rise at 2007 Surf Ave. Sunday, police said.

Guerra leaves behind his wife, Cathy, and four children: Kathleen, 20; Jonathan, 17; Alyssa, 14; and, Zachary, 7.

A 16-year-old resident of the Surf Avenue high-rise, identified by police as Marcell Dockery, was arrested after the fire and was charged Monday with arson, assault and reckless endangerment. A law enforcement official said Wednesday that charges against Dockery will likely be upgraded later this week. Felony murder is a possible charge.

Police Commissioner William Bratton said in a statement released late Wednesday morning: "The death of a police officer as a result of an intentional act not only affects an individual, it is indeed a direct assault upon society as a whole. The entire city grieves this terrible loss. But we can take some measure of solace knowing that an arrest has been made in the arson that took officer Guerra's life and critically injured his partner. . . ."

Meanwhile, Mayor Bill de Blasio asked for a moment of silence for Guerra at the opening of the National Action Network convention, where hundreds in the audience gasped at the news of Guerra's death.

"We in New York City this morning are hurting. ... We lost a good man this morning, a very brave police officer, Officer Dennis Guerra," the mayor said. "He did something that most of us wouldn't understand how to do. We know there was a fire in a housing development on the 13th floor. He ran selflessly toward the flames, selflessly toward the danger, no matter what the risk to him ..."

The mayor ordered all flags be flown at half-staff on all city buildings and stationary flagstaffs throughout the five boroughs.

Outside Guerra's residence in Far Rockaway, a neighbor, who identified himself only as Rafael, recalled the fallen officer teaching his young son to ride a bike -- and said Guerra would shovel his neighbor's sidewalk with a snowblower. "It's really, really sad," he said.

Police said Rodriguez, who was taken to New York-Presbyterian Hospital / Weill Cornell Medical Center in Manhattan, has shown signs of improvement since Sunday. She remained in critical condition Wednesday, and she "continues to battle carbon monoxide poisoning and the effects of severe smoke inhalation," Bratton said in his statement.

"We pray that every young person who hears of the tragic passing of hero police officer Dennis Guerra and of the suffering of officer Rosa Rodriguez and their families, learns that there [are] deadly consequences that result from foolish actions," NYC Patrolmen's Benevolent Association president Patrick Lynch said in a statement Wednesday.

"We must learn from this tragedy so that their sacrifices will not have been made in vain. Our thoughts and prayers are with the Guerra and Rodriguez families, friends and their fellow officers."

De Blasio commended Guerra's bravery and said he's gotten to know Guerra's family in the last few days.

"Officer Guerra was exemplary," the mayor said. "He went to try to save people in need and he has now lost his life."

De Blasio added: "On behalf of all 8.4 million New Yorkers, our hearts go out to the Guerra family. We will stand by them. We will stand by them in their grief and beyond. We'll honor his sacrifice."

In a police radio transmission aired earlier this week on 1010 WINS, Guerra could be heard gasping, "Can't breathe, can't breathe." He and Rodriguez were found unconscious and unresponsive in the hallway by responding firefighters.

Guerra had been transferred to Montefiore from Jacobi Medical Center in the Bronx.

A law enforcement official who didn't want to be named had told Newsday Monday that Guerra needed to be resuscitated a number of times, adding "He is clearly the more serious" of the injured officers.

Dockery lives on the 12th floor of the building where the fire occurred and the law enforcement official also said the teen had a prior juvenile case involving arson that was sealed -- indicating it may have been dismissed. Dockery didn't give authorities a reason for starting the blaze he's accused of starting, the official said, but he seemed "nonchalant" -- and indicated a fascination with fire.

The fire will prompt the NYPD to review procedures to see if any corrective measures or changes in training need to be done, NYPD spokesman Stephen Davis said this week.

According to Davis, the Patrol Guide, the operational manual meant to guide police in their duties, only talks generally about fires and leaves a lot to the discretion of officers on the scene. "Take action as deemed appropriate," was how Davis summarized the overarching Patrol Guide philosophy to fires.

Retired Det. Joseph Giacalone this week told Newsday that adrenaline takes over in such situations, causing officers to sometimes take risks in emergencies. "I have done the same thing," he said. "You don't think of your own safety."

With Darran Simon, Emily Ngo and John Valenti