ARLINGTON, Va. — Crews began removing wreckage from the Potomac River on Monday, five days after 67 people were killed in a midair collision over Washington, D.C., between a passenger jet and an Army helicopter. The crash was the deadliest U.S. air disaster since 2001.

Authorities have recovered and identified 55 of the 67 people killed in the crash and Washington, D.C., Fire and EMS Chief John Donnelly has said they are confident all will be found. Crews early Monday could be seen aboard a vessel with a crane.

More than 300 responders were taking part in the recovery effort at any given time, officials said. Two Navy barges were also deployed to lift heavy wreckage.

Divers and salvage workers are adhering to strict protocols and will stop moving debris if a body is found, Col. Francis B. Pera of the Army Corps of Engineers said Sunday. The "dignified recovery" of remains takes precedence over all else, he said.

Portions of the two aircraft that collided over the river Wednesday night near Ronald Reagan Washington National Airport — an American Airlines jet with 64 people aboard and an Army Black Hawk helicopter with 3 aboard — will be loaded onto flatbed trucks and taken to a hangar for investigation.

The crash occurred when the jet, en route from Wichita, Kansas, was about to land. The Black Hawk was on a training mission. There were no survivors.

On Sunday, family members were taken in buses with a police escort to the Potomac River bank near where the two aircraft came to rest after colliding.

The plane's passengers included figure skaters returning from the 2025 U.S. Figure Skating Championships in Wichita and a group of hunters returning from a guided trip. Army Staff Sgt. Ryan Austin O'Hara, 28, of Lilburn, Georgia; Chief Warrant Officer 2 Andrew Loyd Eaves, 39, of Great Mills, Maryland; and Capt. Rebecca M. Lobach, of Durham, North Carolina, were in the helicopter.

Federal investigators were working to piece together the events that led to the collision. Full investigations typically take a year or more. Investigators hope to have a preliminary report within 30 days.

Wednesday's crash was the deadliest in the U.S. since Nov. 12, 2001, when a jet slammed into a New York City neighborhood just after takeoff, killing all 260 people on board and five on the ground.

Experts stress that plane travel is overwhelmingly safe, but the crowded airspace around Reagan Airport can challenge even experienced pilots.

The NTSB said Saturday that preliminary data showed conflicting readings about the altitudes of the airliner and the helicopter.

Investigators also said that about a second before impact, the jet's flight recorder showed a change in its pitch. But they did not say whether that change in angle meant that pilots were trying to perform an evasive maneuver to avoid the crash.

Data from the jet's flight recorder showed its altitude as 325 feet (99 meters), plus or minus 25 feet (7.6 meters), when the crash happened, NTSB officials told reporters. Data in the control tower, though, showed the Black Hawk at 200 feet (61 meters), the maximum allowed altitude for helicopters in the area.

The discrepancy has yet to be explained.

Investigators said they hoped to reconcile the difference with data from the helicopter's black box and planned to refine the tower data, which can be less reliable.