Triangular shaped brilliant light above roof

There was an extremely bright light coming from the top of our neighbor's house (they are not living there right now). There are trees between our houses, but what I could see was a triangular shaped light (it reminded me of a window right at the peak of a roof, with the light shining from behind it). The light was so bright that it cast shadows in our yard. We have never seen a light that bright that it would light up our yard from that distance. We did not go over to our neighbor's yard to investigate it, but should have. We wish we would have taken a photo of it.