We were camping at the Illinois River, in Selma, Oregon when we heard what sounded like a plane flying over. Four of us were in a tent and first we saw a red light that at first glance appeared to be a plane light very high in the sky, a few seconds later there were 2 more lights flashing behind it and we noticed it was not 2 planes flying in a path high in the sky but 1 large object very low flying just above the treeline!! It appeared to be a vary narrow triangular shape, with 1 red light up near the front & 2 flashing lights in the middle. It flew slow with a loud humming type sound and followed the river to the NW.