An American Airlines passenger jet with 64 onboard was coming in to land at Ronald Reagan Washington national airport when it collided with a military helicopter.

A regional passenger jet with 64 onboard has collided with a military helicopter before crashing into the Potomac river while approaching Ronald Reagan Washington national airport on Wednesday night.

The American Airlines flight, operated by PSA Airlines as American Eagle Flight 5342, had flown from Wichita, Kansas, carrying 60 passengers and four crew members when it collided with a Black Hawk helicopter that was on a training flight.

Dozens of firefighters were “engaged in dive operations” on the Potomac river, Edward Kelly, the general president of the international association of firefighters, said, with bodies reportedly pulled from the water and no survivors being immediately found. US senator Ted Cruz said “we know there are fatalities” but did not provide further details.

The helicopter was believed to be carrying three soldiers, with no senior army officials onboard. The Black Hawk helicopter involved in the crash was based out of Fort Belvoir, Virginia.

Temperatures in the area were below freezing, and any length of time spent in the water would be extremely dangerous for anyone who survived the initial incident, with hypothermia setting in quickly in very cold water.

Inflatable boats and dive teams searched the site, with helicopters circling above, and large floodlights illuminating the scene from the shore. About 300 responders were involved in the search. The operations were made more difficult by strong gusts of wind as well as the cold.

Washington DC fire and emergency medical services chief John Donnelly said: “The challenges are access … there is wind, there [are] pieces of ice out there, so it’s just dangerous and hard to work in.

There was no immediate indication of any deliberate or terrorist cause.

The helicopter was on a training exercise in some of the most tightly controlled airspace in the world. The weather in DC was clear.

All takeoffs and landings have been halted until Thursday morning at the airport while the rescue operation is underway.

President Donald Trump said he had been briefed on the “terrible accident” and praising the “incredible work” done by emergency services. He later said on social media that the crash “should have been prevented”.

Ari Schulman, an eyewitness who was driving home when the incident happened, described 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. It looked like a Roman candle.”.

American Airlines has set up a phone line for relatives who believe they may have lost ones one on board.