ST CLOUD, Dec 6 — A Black Hawk helicopter went down in central Minnesota yesterday, killing all three soldiers on board, after it lost contact with the Minnesota National Guard during a maintenance test flight, Governor Tim Walz said.

Emergency crews gathered at the scene. The names of the crew were not released, but Walz told a news briefing an investigation would be launched into the reasons for the crash.

"At approximately 1400 hours today a Minnesota Army National Guard UH-60 Black Hawk helicopter went down approximately 16 miles south-west of St Cloud,” Walz said, referring to a city in the state's central region.

"The crash resulted in the death of all three crew.'

On Twitter, the Minnesota National Guard earlier said it had lost communication with the craft at about 2pm. — Reuters