All of the passengers aboard an American Airlines flight and an Army Black Hawk helicopter are expected to be dead. Washington D.C. Fire and EMS Chief John Donnelly said on Thursday morning that the search and rescue operation had now changed to a recovery operation.

The plane and the helicopter both landed in the Potomac River. There 64 passengers aboard the plane and three passengers on the helicopter.

28 bodies have been recovered from the river as of Thursday morning. Donnelly added that he’s confident that all the bodies will be recovered, but it could take some time.

At this time it is unclear what caused the crash.