I was with a small group of hunters drinking coffee in the pre-dawn hours, waiting for the sun to rise enough so we could legally hunt deer. Above a range of low hills we saw three spheres hovering, then moving slowly. We estimated distance at about 10 miles from us. Suddenly one sphere increased speed, splitting off from the other two. Of the remaining two, one sphere moved slowly away leaving the third sphere in its original position. After approximately one minute the third sphere quickly took off straight up, then did a 90 degree maneuver left and all three spheres disappeared one after the other. As watchers we at first thought the lights were aircraft from the air base in Great Falls, Montana which is 90 miles from out location, but after witnessing the extreme maneuver of the last sphere and their rapid disappearance we all felt these must be ET.