American Airlines CEO Robert Isom said that Flight 5342 was on a normal approach to Reagan National Airport and that “we don’t know why the military aircraft came into the path of the PSA aircraft,” one of the many questions the Fort Worth-based carrier is asking in the wake of the tragedy that took 67 lives.

Families and friends of those who lost loved ones in the deadly American Airlines and Army helicopter collision are sharing tributes online in memory of the crash victims.