ARLINGTON, Va. — Families of victims of the deadliest U.S. air disaster since 2001 visited the crash site on Sunday and divers scoured the submerged wreckage for more remains after authorities said they’ve recovered and identified 55 of the 67 people killed.

Washington, D.C. Fire and EMS Chief John Donnelly said officials are confident all will be found. Divers are working diligently to locate remains as crews prepare to lift wreckage from the chilly Potomac River near Reagan National Airport as early as this morning, Donnelly said at a news conference.

Col. Francis B. Pera of the Army Corps of Engineers said divers and salvage workers are adhering to strict protocols and will halt work on moving debris if a body is found. The “dignified recovery” of remains takes precedence over all else, he said.

“Reuniting those lost in this tragic incident is really what keeps us all going,” Pera said. “We’ve got teams that have been working this effort since the beginning.”

Federal investigators were working to piece together the events that led to the collision.

The National Transportation Safety Board, which is leading the probe, didn’t hold a press briefing on Sunday, but the agency did release a photograph showing investigators on a small boat looking at wreckage and another of them examining a flight data recorder.

Full NTSB investigations typically take at least a year, though investigators hope to have a preliminary report within 30 days.