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.