A passenger jet carrying 60 passengers and four crew members collided in midair with a military helicopter late Wednesday while landing at Ronald Reagan National Airport in Virginia, near Washington, prompting a large search-and-rescue operation in the nearby Potomac River.

There was no immediate word on casualties, but all takeoffs and landings from the airport were halted as helicopters from agencies across the region flew over the scene in search of survivors.

The U.S. army described the helicopter as a UH-60 Black Hawk based at Fort Belvoir in Virginia. A crew of three soldiers were onboard the helicopter, an army official said. The helicopter was on a training flight.

Inflatable rescue boats were being launched into the river from a point along the George Washington Parkway, just north of the airport, and first responders set up light towers from the shore to illuminate the area near the site of the collision. 

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U.S. President Donald Trump said he had been "fully briefed on this terrible accident" and, referring to the passengers, added, "May God Bless their souls." 

Vice-President J.D. Vance encouraged followers on the social media platform X to "say a prayer for everyone involved."

In an update at about 1 a.m. ET on Thursday, officials including Washington Mayor Muriel Bowser confirmed the number of people onboard both aircraft, but did not provide an update on how many casualties there were after the crash.

"We are going to recover our fellow citizens," Bowser said at a sombre news conference at the airport Thursday morning in which she declined to say how many bodies had been recovered.

Sen. Roger Marshall of Kansas said, "When one person dies it's a tragedy, but when many, many, many people die it's an unbearable sorrow."

Asked if there are any survivors D.C. Fire and EMS chief John A. Donnelly, responded, "We don't know yet. But we're working."

Bowser also declined to comment on the condition of the aircraft, which remains submerged in the Potomac River.

The Federal Aviation Administration (FAA) said the midair collision occurred around 9 p.m. ET when a regional jet that had departed from Wichita, Kan., smashed into a military Black Hawk helicopter while on approach to a runway.

American Airlines Flight 5342 was inbound to Reagan National at an altitude of about 400 feet and a speed of about 140 miles per hour when it suffered a rapid loss of altitude over the Potomac River, according to data from its radio transponder.

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The Canadian-made Bombardier CRJ-701 twin-engine jet was manufactured in 2004 and can be configured to carry up to 70 passengers.

The FAA said it and the U.S. National Transportation Safety Board would investigate.

There are currently about 300 responders working on the rescue operation, including dive teams, according to officials.

Donnelly said at the early Thursday news conference that conditions were "extremely rough for responders," with cold weather and intense wind.

'Tower did you see that?'

A few minutes before landing, air traffic controllers asked the arriving commercial jet if it could land on the shorter Runway 33 at Reagan National and the pilots said they were able to do so. Controllers then cleared the plane to land on Runway 33. Flight tracking sites showed the plane adjust its approach to the new runway.

In audio from the air traffic control tower around the time of the crash, a controller is heard asking the helicopter, "PAT25 do you have the CRJ in sight," in reference to the passenger aircraft.

"Tower did you see that?" another pilot is heard calling seconds after the apparent collision.

The tower immediately began diverting other aircraft from the airport.

In a post on social media, American Airlines said it was aware of reports that one of its flights was involved and said it would provide more information once available.

In a later statement, the airline confirmed there were 60 passengers and four crew on board, and it was assisting with emergency response efforts.

Video from an observation camera at the nearby Kennedy Center shows two sets of lights consistent with aircraft appearing to join in a fireball.

The airport said emergency personnel were responding to "an aircraft incident on the airfield." The airport was to remain closed until 5 a.m. ET Friday. 

Ronald Reagan National Airport, located along the Potomac River just southwest of the city is a popular choice because it's much closer than the larger Dulles International Airport, which is deeper in Virginia.

A CBC News reporter on the scene described an "eerily silent airport," with all the flight information boards being reset to an urgent message.

"Due to an emergency situation, all flights are being held on the airfield," the message read.