A single bright rectangular light descending from the sky

The sky was getting dark with stars just beginning to be visible. We could still see the neighbors house and apple tree clearly. There was a light layer of thin cloud. We were seated & a long rectangular bright light suddenly appeared roughly the height of the power lines above the house roof, traveling downwards in a southerly direction. It was bright and looked like a fluorescent light tube. I ran into the house to get my camera but when I came into the garden the object was disappearing as it moved southwards.