All 64 passengers and crew members aboard an American Airlines regional jet have died after the plane collided midair with a U.S. Army Black Hawk helicopter near Ronald Reagan Washington National Airport on Wednesday night, officials confirmed Thursday.

The crash, which sent both aircraft into the Potomac River, marks the deadliest air disaster on U.S. soil since 2001, according to CNBC.

Washington, D.C. Fire and EMS Chief John Donnelly said at least 28 bodies have been recovered so far—27 from the plane and one from the helicopter.

"We are now at the point where we are switching from a rescue operation to a recovery operation," said Donnely, as reported by the Associated Press.  

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Officials said flight conditions were clear as the American Airlines jet was making a routine landing at Reagan National Airport. The cause of the collision is unclear at this time. 

"On final approach into Reagan National it collided with a military aircraft on an otherwise normal approach," American Airlines Group, Inc. AAL CEO Robert Isom said. "At this time we don't know why the military aircraft came into the path of the … aircraft."

The FAA announced that Reagan National Airport will reopen at 11 a.m. Thursday after flights were grounded following the crash.  

Transportation Secretary Sean Duffy said the appropriate agencies, including the Federal Aviation Administration and U.S. Department of Transportation, are investigating the crash. 

"I would just say that everyone who flies in American skies expects that we fly safely," Duffy said, according to the AP. 

"That when you depart an airport, you get to your destination. That didn't happen last night and I know that President Trump, his administration, the FAA, the DOT, we will not rest until we have answers for the families and for the flying public. You should be assured that when you fly, you're safe," Duffy added. 

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