All 64 people aboard an American Airlines jet that collided with an Army helicopter were feared dead in what was likely to be the worst U.S. aviation disaster in almost a quarter century, officials said Thursday.

At least 28 bodies, including all three soldiers who were on the helicopter, have been pulled from the icy waters of the Potomac River as recovery operations continue.

NTSB Chairwoman Jennifer Homendy said "this is an all-hands-on-deck event."

“We’re here to assure the American people that we are going to leave no stone unturned in this investigation,” she said at a news conference Thursday afternoon at Reagan National Airport.

She also said there were nearly 50 people on scene from the NTSB.

Texas Republican Senator Ted Cruz said he was briefed by the NTSB chairman and senior FAA leaders and said there are still questions about why the helicopter was traveling at a certain altitude and if if the helicopter pilot was looking at the wrong plane.

“We have a very serious investigation that proceeds and that is driven by the facts and evidence,” he said. “I think it is a mistake to speculate until we see what the evidence demonstrates.”