(AP) – The military has now confirmed that four soldiers killed when a helicopter crashed in Afghanistan last week were based in Hawaii. The Army airmen were: Chief Warrant Officer 2 Nicholas Johnson of San Diego, Calif., Chief Warrant Officer 2 Don Viray of   Hawaii, Sgt. Dean Shaffer of Pekin, Ill., and Sgt. Chris Workman of Rupert, Idaho.      Shaffer and Workman were specialists. The Army promoted both to sergeants posthumously.      All were members of the 2nd Battalion, 25th Combat Aviation Brigade based at Schofield Barracks. The brigade is part of the 25th Infantry Division.      They were killed when their Black Hawk helicopter crashed in bad weather during a night flight in Afghanistan on Thursday. The brigade said in a press release Tuesday the cause of the incident is under investigation.