No cause for the crash was provided by army spokesman Aldo Schellenberg, who described it as an "accident" that occurred shortly after takeoff.
Four visiting French military officers had disembarked just before the incident and were unharmed, Schellenberg said.
The accident happened around midday (1000 GMT) in the remote Gotthard Pass in the Ticino canton near a hospice that stands at an altitude of 2,100 metres (6,900 feet).
"The two pilots did not survive the accident," the army spokesman said, identifying the injured person as a "flight assistant", who was taken to a hospital.
The helicopter involved was an Airbus-made Super Puma.
The Swiss army has grounded all Super Pumas until the causes of the accident have been identified, Schellenberg said.
At the end of August, a Swiss pilot died after crashing his F/A-18 in the Hinter-Tierberg region, apparently after flight controllers gave him incorrect altitude instructions.
In June, two Swiss Tiger F-5E fighter jets collided in the Netherlands in June during a training flight for an air show.
And during another training exercise in October last year, an F/A-18 crashed in an uninhabited part of France's eastern Doubs region.
No one was hurt on the ground and the pilot was only slightly injured after ejecting from the plane.
The last similar helicopter crash for the army came in March of 2011 in central Switzerland's Uri canton.
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