Army officials say five US soldiers based at Fort Riley, Kansas, and one based in Europe were killed in a helicopter crash this week in southern Afghanistan.

The Army on Thursday confirmed the soldiers died when their Black Hawk UH-60 went down Tuesday during a mission. One soldier survived the crash.

The five Fort Riley soldiers were identified as Chief Warrant Officer 2 Randy Billings of Heavener, Oklahoma; Chief Warrant Officer 2 Joshua Silverman of Scottsdale, Arizona; Sgt Peter Bohler of Willow Spring, North Carolina; Sgt 1st Class Omar Forde of Marietta, Georgia; and Spc Terry Gordon of Shubuta, Mississippi.

A sixth soldier, based in Vilseck, Germany, was identified as Staff Sgt Jesse L Williams, 30, of Elkhart, Indiana.

Fort Riley confirmed that a seventh soldier was injured in the crash, although officials there said they could not release a name because of privacy reasons. Military officials said the cause of the crash remained under investigation.

Major General Paul Funk II, commanding general of the 1st Infantry Division and Fort Riley, offered condolences to the soldiers' families and friends.

"We stand ready to support them and I urge our community and the nation, while remembering their sacrifices this holiday season, to do the same," Funk said in a statement.

The deputy governor of southern Zabul province said Wednesday that a NATO helicopter crashed in the remote district of Shajau and US officials later confirmed that Zabul was the location of the US crash.

"The loss of six US troops in a helicopter crash on Tuesday is a heartbreaking reminder of the sacrifices" the men and women serving in Afghanistan continue to make, Defense Secretary Chuck Hagel said Thursday during a Pentagon press conference that covered a range of issues. "And our thoughts and prayers go out to their families."

The 1st Division Combat Aviation Brigade sent some 2,000 soldiers to Afghanistan in August for a nine-month deployment, replacing the 3rd Infantry Division's Combat Aviation Brigade. According to a brigade news release in September, the soldiers are responsible for providing air support over a mountainous and desert region roughly the size of Montana.