(Loveday Morris/The Washington Post)

Iraqi rescue workers on Friday pulled dozens of bodies from the ruins of a building in Mosul where residents allege a U.S.-led coalition strike killed 137 people a week ago.

If confirmed, the number would mark the biggest loss of civilian life in a single incident since the coalition’s air campaign began 2½ years ago.

Equipped with a bulldozer and chain saws, men in red overalls picked their way through the rubble of the large house in the city’s heavily bombarded neighborhood of Mosul al-Jadida.

Brig. Gen. Mohammed Mahmoud, Mosul’s civil defense chief, said families had gathered in the building because it was one of the few with a basement. His team had retrieved the bodies of 61 people, including two babies, from the rubble over the past two days. But he said he expected dozens more bodies to be found as the excavation continued, with rescue workers yet to reach the basement or other collapsed rooms.

“There’s a whole room at the back full of women,” he said. “They are all burned. We are trying to get them out.”

The leg of a dead man protruded from the detritus nearby, a sock still on his foot.

Mahmoud said the building was evidently hit by an airstrike. “We are experts in this field,” he said. “We know it’s the coalition. We demand an investigation.”

While Iraqi jets also carry out strikes in Mosul, the coalition usually gives close air support to the counterterrorism forces that were advancing in the area at the time.

In a statement, the U.S.-led ­coalition said that it had received multiple “conflicting allegations” placing a strike in the area sometime between March 17 and 23, and that it was investigating the reports. It added that the process “takes time” — especially when the date of the alleged strike is in question.

“We will continue to assess the allegations and determine what if any role a coalition strike may have had in that area,” the statement said. “Coalition forces work diligently to be precise in our airstrikes.”

Residents said there were strikes over several days as Iraqi government forces advanced against Islamic State fighters.

On the adjacent street, where building after building had been destroyed, families dug bodies from the rubble, zipped them into blue body bags and pushed them away on wooden carts.

Members of the civil defense search for bodies in the rubble of a building in the Mosul al-Jadidah neighborhood of Mosul, Iraq, on March 24, 2017. (Alice Martins/For The Washington Post)

Mahmoud said a total of 156 bodies had been recovered from about 10 houses so far. He added, though, that it was not clear who was responsible for all of the destruction because fighting has been heavy in the neighborhood, with militants using car bombs and heavy weaponry. Residents said the Islamic State fighters would not let people leave and had moved families from outside into the area to use as human shields as they fought from residents’ roofs.

As U.S.-backed forces close in on both Mosul and the Syrian city of Raqqa, allegations of heavy ­civilian casualties have soared. Airwars, an organization based in Britain that monitors claims of civilian casualties, said Friday that 1,000 civilians were allegedly killed in coalition airstrikes in the two countries this month. The group said it had suspended its detailed case-by-case assessments of Russian airstrikes to focus its limited resources.

President Trump has asked for a reassessment of battlefield rules of engagement as part of his plan to defeat the Islamic State, although U.S. and Iraqi officials say the rules have not changed.

Instead, Iraqi commanders say, the militants are increasingly putting civilians in harm’s way, rounding up families and keeping them inside houses as the militants fight from the rooftops.

Marwan Salem, 50, said that six of his relatives — including his daughter, her husband and their 1-month-old baby — were among the 137 killed last week in the Friday morning strike. None of their bodies had been recovered a week later.

“They are deep inside,” he said, looking toward the destroyed building across the street.

Next to him sat Faris Hussein, 51, who said he had lost 30 family members. Twelve bodies had been recovered, he said.

Iraq’s Joint Operations Command did not directly confirm or deny the strike but said Islamic State militants have been “heinous” in their treatment of civilians, fighting from their houses or using the residences as bases from which to launch suicide attacks.

Brig. Gen. Falah al-Obaidi, a commander with counterterrorism forces that were advancing at the time, said the buildings in the area collapsed when a guided missile hit a car bomb, causing a large explosion near the homes.

“These things happen, but we try to reduce casualties as much as we can,” he said. The forces in his sector had paused operations Friday to allow civilians to leave safely. Residents made their way through bombed-out streets to safety, carrying what they could with them.

Obaidi said that the Islamic State was trying to increase civilian casualties to “mislead public opinion.”

There was no car-bomb crater on the street, and amid the conflicting allegations, Iraqi security forces tried to restrict access to the area and asked journalists to leave.

The civil defense operation had brought workers up from the capital, Baghdad, to assist with pulling people from the crumpled remains of buildings, but had a team of only 50 and one bulldozer and crane, not enough to deal with the needs of the entire city, Mahmoud said.

On the adjacent street, residents described more misery as the smell of decomposing bodies hung in the air. Ihab Adnan was finishing removing 27 of his relatives who had been killed in his grandfather’s house in an airstrike on March 14 — a date outside the time frame the U.S.-led coalition is investigating.

His relatives, wearing medical masks to block the smell, carted seven of the bodies down the bombed-out street for burial. Other remains lay in body bags nearby. The 31-year-old said he was in his house on the opposite side of the street when the missile hit. He rushed outside and pulled 10 people from the rubble, he said, describing the scene as “hell.”

“There were so many explosions,” he said. “It was truly terrifying.”

The militants had positioned a sniper on a roof nearby and had been moving in and out of the houses before the airstrike, Adnan said, adding that militants prevented families from leaving the area and had gathered others from nearby neighborhoods.

The blast that killed his grandfather, aunts, uncles, nephews and nieces ripped the sides off his house, too, although no one inside was seriously injured.

About 50 meters farther along the street, Mohammed Tinuq said his two brothers and their families — a total of 19 people — were also killed.

“The bombing was very tough,” he said. “They used them as human shields.”

The United Nations said it expects the plight of civilians to worsen as security forces reach the packed and narrow streets of ­Mosul’s Old City — where U.N. estimates say 400,000 civilians are trapped. Some 150,000 have fled the western side of the city into camps.

“It was like World War Three,” said Ibrahim Ahmed Taher, 51, who walked several miles out of the area Thursday. His son was killed in an airstrike, he said.

“So many families are trapped under the rubble.”