A PSA Airlines Bombardier CRJ700 collided midair with a Sikorsky H-60 helicopter over the Potomac River near Ronald Reagan Washington National Airport. At least one aircraft reportedly plunged into the river, prompting a major emergency response. The FAA temporarily closed the airport, while a multi-agency search and rescue operation is underway. No immediate information is available on casualties or survivors. The NTSB will investigate the cause of the collision.