A passenger jet carrying 64 people crashed into Washington's Potomac River Wednesday after colliding midair with a military helicopter, with US media reporting multiple bodies pulled from the dark, near-freezing water.
The plane was approaching Reagan National Airport at around 9:00 pm (0200 GMT) after flying from Wichita, Kansas, when the collision happened.
American Airlines subsidiary PSA Airlines, which operated the Bombardier regional jet, said "there were 60 passengers and four crew members on board the aircraft."
US media, citing local sources, reported multiple bodies had been recovered, with CBS News saying at least 18, and NBC more than a dozen.
The Washington Post, citing a statement from US Figure Skating, said several athletes, coaches and officials were aboard the flight.
A US Army official said the helicopter involved was a Black Hawk carrying three soldiers, with their status currently unknown. They had been on a "training flight," a separate military spokesperson said in a statement.
A massive search and rescue operation was in progress, with divers visible in the glare of powerful lights as they plunged into the snow-lined Potomac to scour the wreckage of both aircraft.
"We're going to be out there as long as it takes, and we're obviously trying to get to people as soon as possible, but we are going to recover our fellow citizens," Washington Mayor Muriel Bowser told reporters.
Washington Fire Chief John Donnelly said at a press briefing that emergency crews, totaling about 300 people, were working in "extremely rough" conditions and gave little indication they expected to find anyone alive.
"We will re-evaluate where we are with the rescue operation in the morning, when we get a better sense of it," Donnelly said.
"But we are still out there working, and we're going to continue that throughout the night."
Witness Ari Schulman was driving home when he saw what he described as "a stream of sparks" overhead.
"Initially I saw the plane and it looked fine, normal. It was right about to head over land," he told CNN.
"Three seconds later, and at that point it was banked all the way to the right... I could see the underside of it, it was lit up a very bright yellow, and there was a stream of sparks underneath it," Schulman added.
"It looked like a Roman candle."
The Federal Aviation Administration ordered the grounding of all planes at Reagan National and the airport was not due to reopen until 11:00 am (1600 GMT) Thursday.
American Airlines' chief executive issued a video statement in which he expressed "deep sorrow", while US Senator Roger Marshall of Kansas called the collision "nothing short of a nightmare."
Questions were expected to focus on how a passenger plane with modern collision-avoidance technology and nearby traffic controllers could collide with a military aircraft over the nation's capital.
The airspace around Washington is often crowded, with planes coming in low over the city to land at Reagan Airport and helicopters -- military, civilian and carrying senior politicians or officials -- buzzing about both day and night.
The same airport was the scene of a deadly crash in January 1982 when Air Florida Flight 90, a Boeing 737, took off but quickly plummeted, hitting the 14th Street bridge and crashing through the ice into the Potomac River. Seventy-eight people died.
Investigators concluded the pilot had failed to activate sufficient de-icing procedures.
The last major fatal US air accident was in 2009, when Continental Flight 3407 from New Jersey to Buffalo, New York crashed and killed all 49 people aboard.
I'm quite certain that is the Pareto Principle.
Nope that's the Heisenberg hypothesis, the Party Principle says you never have enough popcorn. Or was it strippers and blackjack?