Investigators trying to figure out what led to the deadly midair collision between a US military Black Hawk helicopter and an American Airlines plane near Washington, DC, last week will brief lawmakers Thursday on what they’ve learned after combing through data from both aircraft and air traffic control.

Officials say the bodies all 67 passengers involved in the Washington, D.C. midair collision have been recovered from the Potomac River. It comes as new details on the investigation are emerging, including that the Black Hawk helicopter involved in the crash was flying at 300 feet.