An American Airlines regional jet went down in the Potomac River near Ronald Reagan Washington National Airport.

Sixty passengers and four crew members from the plane and three Black Hawk helicopter personnel are feared dead as a recovery mission is underway.

Get all the news you need in your inbox each morning. Federal aviation investigators vowed earlier in the day that they will find the cause of a horrific collision. NTSB Chairwoman Jennifer Homendy said at a briefing that the agency wants to assure the American public it will "leave no stone unturned in this investigation .