The only firefighters in West Mosul, Iraq, switched on the siren as they drove a battered red truck through the ruins of their city. It was the morning of April 16, and they led a small convoy along roads gouged by bombs and partially blocked by collapsed buildings. The fighting was finished in this neighborhood, and the only other vehicles around were mangled wrecks. But the siren was an old habit, and it felt good to be back at work.

The firefighters, members of what is known in Iraq as the Civil Defense, parked by a colossal crater, and their chief, 47-year-old Colonel Rabie Ibrahim Hassan, started out on foot up an unpaved side street. Skinny, square-jawed Mohammed Shabaan hurried after him, clutching a small notebook. Around a dozen other men followed, guiding a crane and frontloader almost too large to fit between the buildings.

It had rained for weeks, but the day broke dry and hot and the now-still air smelled of corpses. The men pulled cheap surgical masks or respirators over their faces as they walked. They stopped in front of a heap of concrete and metal that had once been a pink two-story house. The background of gunfire and thud of mortar shells was louder here, as Iraqi forces clawed back ground from ISIS after an almost three-year occupation. Nobody seemed to notice the noise; it had been that way for months.

Civil Defense member Salih Jumma leaps from one of the group's tanker trucks as they attempt to repair it after finding it abandoned in a junkyard. John Beck Salih Jumma rests after recovering bodies from the rubble of an airstrike during an operation in West Mosul. John Beck

First in was Salih Jumma, the team's bomb-defusal expert. He had once been an enthusiastic brawler and was widely known by a nickname that roughly translates as "the hard man." Now 43, he was still strong, heaving aside chunks of concrete that others struggled to move in pairs.

Jumma disturbed a glistening mass of flies that shrouded the body of an ISIS fighter half buried in cinder blocks. The militant's face was decayed and swollen, and he was wearing a soiled blue coat and striped polo shirt. A suicide rig of explosives linked to a yellow detonation cord was wrapped around his waist. Jumma stiffened when he noticed. "Careful," he shouted. "He's wearing a belt." The firefighters stepped back—though not far enough to be safe—and conferred briefly. Jumma returned, uncovered more of the body, and tied a rope to its ankles, then looped the other end around the crane's hook. They watched the body rise slowly into the air, skim telephone wires, and come to rest in the courtyard of an empty house across the street.

Then the real work began—not fighting fires (there was hardly anything left to burn) but rather smashing through concrete with the frontloader, slicing the rebar inside, and hauling sections clear. The smell thickened as they drew closer to the object of their search: a family crushed under the rubble.