The two black boxes have been recovered from the plane that crashed after colliding with a military helicopter near the US capital in Washington, D.C., a government agency said Thursday.

The National Transportation Safety Board (NTSB) said its investigators recovered the cockpit voice recorder and flight data recorder from the Bombardier CRJ700 airplane involved in Wednesday's mid-air collision at Ronald Reagan National Airport.

"The recorders are at the NTSB labs for evaluation," the NTSB said in a statement.

The NTSB is an independent government investigative agency responsible for civil transportation accident investigation.

The American Airlines plane had 60 passengers and four crew on board when it collided in midair with an Army Black Hawk helicopter carrying three soldiers. Both aircraft crashed into the Potomac River.

During a press briefing at the White House earlier in the day, President Donald Trump said that no one survived the crash.

Citing a law enforcement source, CBS News reported that at least 40 bodies had been recovered by 5.30 pm Eastern Time.

It also reported that 14 figure skaters were among the victims of the crash, with Skating Club of Boston CEO Doug Zeghibe saying that six of the victims were from the Boston club, including two coaches, two teenage athletes and two mothers of athletes.

There were also skaters from Russia.

The New York Times reported that staffing at the air traffic control tower at the airport was "not normal for the time of day and traffic volume.”

Citing a preliminary safety report by the Federal Aviation Administration (FAA) on the collision, it said that a single controller was handling communications for both helicopters and planes, a task usually divided between two people.