US President Donald Trump said there were no survivors of Wednesday's midair collision between a passenger jet and a military helicopter. A total of 67 people are feared dead.

Trump made the comments at a news conference in Washington on Thursday.

He said, "This was a dark and excruciating night in our nation's capital and in our nation's history, and a tragedy of terrible proportions."

Trump said the cause of the accident is not yet known but announced an investigation to "get to the bottom of it." He said he would appoint an acting commissioner of the Federal Aviation Administration with more than two decades of experience.

The collision occurred when the passenger jet was approaching Ronald Reagan National Airport. Video shows the plane and the helicopter falling into the Potomac River following the accident. The jet was carrying 64 passengers and crew, including members of a figure-skating team. The helicopter had three service members on board.

Secretary of Defense Pete Hegseth commented that the troops were taking part in a training session. He said: "It was fairly experienced crew, and it was doing a required annual night evaluation. They did have night vision goggles."

He added that investigators will look into whether the helicopter was flying at the proper altitude.