ATLANTA — Officials have shut down Ronald Reagan National Airport until 11 a.m. Thursday after an American Airlines passenger jet and Army helicopter collided over the Potomac River in Washington D.C.

Southwest Airlines (NYSE:LUV) shares fell around 3% in premarket trading Thursday after the company reported fourth-quarter earnings above analyst estimates, but the revenue came in short.

The U.S. Army described the helicopter as a UH-60 Blackhawk based at Fort Belvoir in Virginia. The helicopter was on a ...