If changes aren't made, that near-miss becomes a mid-air collision,” one aviation safety expert said. “Unfortunately, that's what we had last night.”

The deadly mid-air collision over Washington, D.C., has reignited concerns over air traffic congestion and safety risks at Ronald Reagan Washington National Airport, a tightly packed aviation hub that shares airspace with military and government flights.

There was no immediate word on the cause of the collision, but all takeoffs and landings from the airport were halted as dive teams scoured the site and helicopters from law enforcement agencies across the region flew over the scene in a methodical search for bodies.

A deadly plane crash over the Potomac River near Washington, D.C. canceled flights to and from Ronald Reagan National Airport overnight. The airport reopened around 11 a.m. Thursday, as the search continues for the 64 people on board the American Airlines plane that collided with a U.