The families of the people who died in a mid-air collision between an American Airlines jet and a U.S. Army Black Hawk helicopter are accusing the Army of refusing to take responsibility or engage with them.

Relatives of the victims sent a letter to the Secretary of the Army accusing the military of stonewalling their efforts to get answers.

Sixty-seven people died when the jet, which had taken off from Wichita, and the Black Hawk helicopter collided mid-air in Washington, D.C.