This is the dramatic moment a metro train turned around when an announcement informed passengers that airport services were suspended following a crash between a helicopter and a plane.

All flights were halted and search teams began scouring the Potomac River after the collision with the plane that was landing at the Reagan National Airport near Washington on Wednesday night.

Footage captured by Sarah Fishel shows the moment the announcement was made, leaving commuters surprised as the train changed course.

Footage from an observation camera at the nearby Kennedy Centre and CCTV cameras captured a fireball followed by a cloud of smoke. Drivers also captured the crash on dashcam cameras.

The Bombardier CRJ-700 was being flown by American Eagle, a regional brand of American Airlines, with 60 passengers and four crew onboard.

Records show that Flight 5342, being operated by PSA Airlines, was flying from Wichita, Kansas (ICT) to Washington Reagan National Airport (DCA).

It was on approach to the runway when the helicopter approached from the starboard side and smashed into the aircraft, shortly before 9 pm local time.

The White House confirmed the commercial airliner collided with a military helicopter while on approach to Reagan National Airport

The Federal Aviation Administration said the helicopter was a Black Hawk.

The FAA said an investigation has been launched. All take-offs and landings from the airport near Washington have been halted.

Ronald Reagan National Airport is in the centre of the nation's capital, near major federal institutions including the White House and Congress. It is also across the river from The Pentagon, the US Department of Defence, in Arlington, Virginia.