An American Airlines plane with 60 passengers and four crew members on board collided with a military helicopter near Washington, D.C., on Wednesday night, plunging into the Potomac River.

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,

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