Three U.S. Army soldiers were onboard a BlackHawk helicopter that collided with a passenger jet near Ronald Reagan Washington National Airport, U.S. officials said on Wednesday.

Family members of the victims of the plane crash in Washington, D.C., visited the crash site on Sunday morning. Dozens of the victims' loved ones could be seen gathered by the Potomac River to commemorate the 67 people killed in the deadly midair collision last week.

Families of victims of the deadliest U.S. air disaster in a nearly in 25 years visited the crash site just outside Washington, D.C.

Investigators have also located the aircraft's black box, CBS reports. It could provide clues into the cause of the crash.

All six people aboard the plane − a pilot and copilot, two medical personnel, a patient and her mother − died in the crash Friday.