WASHINGTON — A jet carrying 60 passengers and four crew members collided Wednesday with an Army helicopter while landing at Ronald Reagan National Airport near Washington, prompting a large search-and-rescue operation in the nearby Potomac River.

There was no immediate word on casualties or the cause of the collision, but all takeoffs and landings from the airport were halted as helicopters from law enforcement agencies across the region flew over the scene in search of survivors. Inflatable rescue boats were launched into the Potomac River from a point along the George Washington Parkway, just north of the airport.

The Federal Aviation Administration said the midair crash occurred around 9 p.m. EST when a regional jet that had departed from Wichita, Kansas, collided with a military Blackhawk helicopter while on approach to an airport runway. It occurred in some of the most tightly controlled and monitored airspace in the world, just over three miles south of the White House and the Capitol.

Investigators will try to piece together the aircrafts’ final moments before their collision, including contact with air traffic controllers as well as a loss of altitude by the passenger jet.

American Airlines flight 5342 was inbound to Reagan National at an altitude of about 400 feet and a speed of about 140 miles per hour when it suffered a rapid loss of altitude over the Potomac River, according to data from its radio transponder. The Canadian-made Bombardier CRJ-701 twin-engine jet was manufactured in 2004 and can be configured to carry up to 70 passengers.

A few minutes before landing, air traffic controllers asked the arriving commercial jet if it could land on the shorter Runway 33 at Reagan National and the pilots said they were able. Controllers then cleared the plane to land on Runway 33. Flight tracking sites showed the plane adjust its approach to the new runway.

Less than 30 seconds before the crash, an air traffic controller asks the helicopter if it has the arriving plane in sight. The controller makes another radio call to the helicopter moments later: “PAT 25 pass behind the CRJ.” Seconds after that the two aircraft collide.

The plane’s radio transponder stopped transmitting about 2,400 feet short of the runway, roughly over the middle of the river.

Video from an observation camera at the nearby Kennedy Center showed two sets of lights consistent with aircraft appearing to join in a fireball.

The crash is serving as a major test for two of the Trump administration’s newest agency leaders. Pete Hegseth, sworn in days ago as defense secretary, posted on social media that his department was “actively monitoring” the situation that involved an Army helicopter. Transportation Secretary Sean Duffy, just sworn in earlier this week, said in a social media post that he was “at the FAA HQ and closely monitoring the situation.”

Reagan National is located along the Potomac River, just southwest of the city. It’s a popular choice because it’s much closer than the larger Dulles International Airport, which is deeper in Virginia.

Depending on the runway being used, flights into Reagan can offer passengers spectacular views of landmarks like the Washington Monument, the Lincoln Memorial, the National Mall and the U.S. Capitol. It’s a postcard-worthy welcome for tourists visiting the city.

The incident recalled the crash of an Air Florida flight that plummeted into the Potomac on January 13, 1982, that killed 78 people. That crash was attributed to bad weather.

The last fatal crash involving a U.S. commercial airline occurred in 2009 near Buffalo, New York. Everyone aboard the Bombardier DHC-8 propeller plane was killed, including 45 passengers, 2 pilots and 2 flight attendants. Another person on the ground also died, bringing the total death toll to 50. An investigation determined that the captain accidentally caused the plane to stall as it approached the airport in Buffalo.