It has been nearly a week since a commercial jetliner and an Army helicopter collided in midair near Washington’s Ronald Reagan National Airport, killing 67 people in the deadliest U.S. air disaster since 2001. Even as salvage crews continue to haul the wreckage out of the Potomac River, investigators are seeking answers about what happened.

As reported by American media, authorities have recovered the bodies of all 67 victims from the Potomac River in Washington, less than a week after an American Airlines plane collided with a military helicopter.