There are confirmed fatalities from the collision of American Airlines Flight 5342 and the U.S. Army Black Hawk helicopter over the Potomac River. Several bodies have been pulled from the Potomac River crash site, according to two law enforcement sources familiar with the ongoing operation.

U.S. authorities said on Thursday it was not yet clear why a regional jet and a U.S. Army helicopter collided at a Washington airport, killing 67 people in the deadliest U.S. air disaster in more than 20 years.

An American Airlines plane carrying 60 passengers and four crew members collided with an Army Black Hawk helicopter outside Reagan National Airport near Washington, D.C. Wednesday night. A D.C. fire official said Thursday that “we don't think there are any survivors from this accident" and "we are switching from a rescue operation to a recovery operation.