The Medical Emergency Response Team helicopter was called, but sadly the soldiers were all pronounced dead by the doctor in the helicopter.
Spokesperson for Task Force Helmand, Commander Paula Rowe, said:
"Today has been incredibly sad for the whole of Task Force Helmand, and particularly for The Rifles.
"We will all feel the loss of these brave soldiers, whose role was to build the capacity of the Afghan National Army. But it is their family, friends and loved ones, as well as the men and women who served alongside them, who feel the greatest pain and we offer them our deepest and heartfelt condolences, thoughts and prayers."
Next of kin have been informed and have asked for a period of grace before further details are released.