Investigators have recovered the flight recorders—also known as black boxes—from both the commercial jet and the military helicopter involved in the mid-air collision near Reagan National Airport in Washington,

Divers are expected to return to the Potomac River as part of the recovery and investigation after the United States’ deadliest aviation disaster in almost a quarter century.

Rescue crews will return to the Potomac River on Friday morning as they continue searching for victims of Wednesday night’s deadly midair collision.