At least 55 victims have been positively identified from Wednesday night's midair collision between an American Airlines jet and a military Black Hawk helicopter, Fire Chief John Donnelly of the Washington, D.C., Fire Department said Sunday afternoon.

Donnelly said 11 separate sets of remains were recovered from the water on Saturday but have yet to be positively identified.

"It is my belief that we're going to recover everyone," Donnelly said.

Col. Francis Pera of the U.S. Army Corps of Engineers, Baltimore District, said crews are scheduled to begin lifting large pieces of the wreckage of both aircraft from the water at dawn on Monday after spending two days surveying the debris field and rehearsing how the recovery of the wreckage will go.

Pera said wreckage will be placed on flatbed trailers and taken to a nearby hanger for investigators to analyze.

Pera said that if crews come upon more human remains, the salvage teams are prepared to pause the operation to facilitate a "dignified recovery" of the victims.

Family members of the plane crash victims visited the crash site on Sunday morning.

Dozens of the victims' loved ones could be seen gathered by the Potomac River to commemorate the 67 people killed in the deadly midair collision last week.

The Army Corps of Engineers has released a timeline for removing the jet and helicopter wreckage from the Potomac River.

Salvage operations are set to begin on Monday, Feb. 3, according to the tentative timeline.

“The initial focus is removal of the remnants of the regional jet, which is expected to take three days," the Army Corps of Engineers said in a news release.

After that, crews will begin work to recover the Black Hawk helicopter.

"Large lifts" are expected to be completed by Saturday, Feb. 8, after which crews will focus on clearing remaining debris with salvage baskets.

The effort is expected to be completed by Feb. 12.

-ABC News' Luis Martinez

NTSB investigator J. Todd Inman got emotional when asked about his interactions with the victims' families and others who have been directly impacted by the incident.

"They're all just hurt and they want answers and we want to give them answers," he said. "It's horrible. No one has to suffer this."

Inman held up a challenge coin that he had in his pocket with the inscription, "From tragedy we draw knowledge to improve the safety for us all."

"We need people to take action," he said noting hundreds of recommendations that his agency has made following several transportation-related incidents.

"Adopt the recommendation of the NTSB. You'll save lives. I don't want to meet with those parents again," Inman added.

President Donald Trump posted on social media overnight, "This is a bad situation that looks like it should have been prevented."

Asked about Trump’s comments, Transportation Secretary Sean Duffy told reporters Thursday, "To back up with the president said, what I've seen so far -- do I think this was preventable? Absolutely."

Duffy said that "everything was standard in the lead up to the crash."

"It is not standard to have aircraft collide. Want to be clear on that, but prior to the collision, the flight paths that were being flown from the military and from American that was not unusual for what happens in the D.C. airspace," Duffy added.

Duffy said that there was no breakdown of communication.

"I don't want to say too much on the communication between the helicopter and the tower and the airline and the tower, but I will say this: There was communication," Duffy said. "It was, I would say, standard communication, so there was not a breakdown" in communication.

"The helicopter was aware that there was a plane in the area," he said.

Officials did not give any information on the flight history and experience of pilots on both aircraft, but did say that the captain had over six years of experience with the airline and the first officer had almost two years.

Runway operations at the airport are expected to resume at 11 a.m.

-ABC News' Ayesha Ali