An American Airlines plane with 64 people on board collided with an Army helicopter near Washington, D.C., and crashed into the Potomac River.

Recovery crews are now awaiting heavy machinery, including cranes, from the Army Corps of Engineers, Coast Guard and private contractors before they can extract additional victims, sources familiar with the operation told ABC News.

Divers are expected to return to the Potomac River as part of the recovery and investigation after the United States’ deadliest aviation disaster in almost a quarter century.