Officials said that four crew members were from the New York unit. The others onboard included a combat rescue officer, and active and reserve airmen, whose job is to find and recover downed aircrews and evacuate the wounded.

As the hours passed on Friday, the names and backgrounds of the two victims came into focus.

One, Christopher J. Raguso, 39, was appointed as a firefighter in 2005, and worked for many years in Ladder Company 113 in Flatbush, Brooklyn, before being promoted to lieutenant in 2016, and going to work in Queens. Decorated six times for bravery and saving lives, he was a volunteer firefighter on Long Island, where he lived with his wife, Carmella, and two young daughters.

It was in a Facebook post by the volunteer fire department in Commack, N.Y., that Lieutenant Raguso’s life began to emerge publicly. He died “while protecting our freedom,” the post said. It featured two photos of him: one in the dress blues of his municipal uniform and another in an airman’s camouflage.

The post went on: “Chris was always there to help anyone with anything, he would never say no.”

Another local volunteer department, in Northport, N.Y., posted more photos of Lieutenant Raguso. And a local news website posted a video of an interview Lieutenant Raguso gave in August to a Texas television station, in which he spoke of his efforts to help rescue people battered by the floods of Hurricane Harvey.

The other New York City firefighter who died was identified by his parents and city officials as Christopher Tripp Zanetis, 37, who was on leave from the department, where he had been a marshal in the Bureau of Fire Investigation.