Washington DC/IBNS: US president Donald Trump has said the midair collision between American jet and Army chopper "should have been prevented" amid the ongoing efforts to rescue the people who were onboard.

Reacting to the collision, Trump wrote on Truth Social, "The airplane was on a perfect and routine line of approach to the airport. The helicopter was going straight at the airplane for an extended period of time. It is a CLEAR NIGHT, the lights on the plane were blazing, why didn’t the helicopter go up or down, or turn.

"Why didn’t the control tower tell the helicopter what to do instead of asking if they saw the plane. This is a bad situation that looks like it should have been prevented. NOT GOOD!!!"

An American Airlines Flight carrying 64 people collided with an Army chopper with three soldiers onboard midair near the Ronald Reagan Washington National Airport and both crashed into the Potomac River of Washington D.C. on Wednesday.

Eighteen bodies have been recovered so far. Many feared dead while no official confirmation has arrived yet.

The effort to rescue people from the river is underway.

About 300 first responders are searching for the bodies in the freezing river, said DC Fire chief John A. Donnelly.

"The challenges are access. The water that we’re operating in is about 8 feet deep, there is wind, there is pieces of ice out there so it’s just dangerous and hard to work in," Donnelly said as quoted by CNN.

"The water is dark, it is murky, and that is a very tough condition for them to dive in," he added.

All airport entrances have been closed.

Washington DC mayor Muriel Bowser said she couldn't provide any timeline for the rescue operation and first responders would be on their job till all the passengers of the aircraft are traced.

Donnelly couldn't provide any confirmation on the casualty. "We don't know if there are survivors," he said.

"We will re-evaluate where we are with a rescue operation in the morning, when we get a better sense of it," the DC Fire chief added as quoted by BBC News.

Donnelly cited lack of light, wind and freezing water as the main challenges to the search operation.

Metropolitan Washington Airport Authority president Jack Potter said 19 aircrafts were diverted from the Reagan airport to Dulles International Airport which is nearby.