Olathe ? A 21-year-old Kansas soldier was among 30 U.S. troops killed when a helicopter was shot down in Afghanistan.

Chief Warrant Officer Michael Walsh said Sunday that Specialist 4 Spencer C. Duncan was serving as a door gunner on the CH-47 helicopter that was hit by rocket fire Saturday.

Walsh said Duncan, who graduated from Olathe South High School, was a member of Bravo Company, 7th Battalion, 158th Aviation Regiment based at New Century AirCenter in Gardner.

Duncan joined the military in 2008 and had been in Afghanistan since late May. He was stationed at Forward Operating Base, Shank.