The National Transportation Safety Board plans to have a preliminary report on the mid-air collision between a passenger plane and a military helicopter within 30 days.

Officials stressed that it would take time to gather accurate information about the deadly incident.

"We need to verify information. We need to take our time to make sure it is accurate," NTSB Chair Jennifer Homendy told reporters.

Everyone on board the passenger jet and Black Hawk helicopter that collided near Reagan National Airport in Arlington, Virginia, on Wednesday, has died, President Donald Trump confirmed on Thursday.

Washington, D.C., Fire Chief John A. Donnelly Sr. said Thursday that more than two dozen bodies were pulled from the jet and one body was recovered from the helicopter.

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NTSB member Todd Inman said the agency is now working with parties including the manufacturers and operators of the involved aircraft, the Federal Aviation Administration, unions for the involved pilots and air traffic controllers and representatives from the Army. Inman said these parties will not release information relating to the incident except through the NTSB.

Information about victims killed in the crash will be released through the Washington, D.C. medical examiner.

The NTSB will work to reconstruct the flight paths of the aircraft, review ATC systems and communications, and investigate engines and systems aboard the aircraft involved in the crash.

Groups will also review the efforts of first responders and the background, health history and work environment of ATC personnel, pilots and crew.

NTSB has not yet recovered flight data recorders from either aircraft. The agency believes both recorders to be underwater in the Potomac River.

"Nothing we've seen would indicate that maybe slides or chutes were deployed" from the airliner at the time of the crash, Inman said. But he reiterated, "We still have to verify all of that information."