Data from air traffic control radar showed the military chopper was flying at 300 feet on the air traffic control display at the time of the fiery crash, according to the NTSB.

Sixty passengers and four crew members from the plane and three Black Hawk helicopter personnel were killed, and a recovery mission is underway.

Victims' families gathered near the site where a plane and copter collided and fell into the Potomac River. 'They are all hurt,' an official said.