Silent white light slowly flew over my building.

I was watching TV while laying on the floor and noticed a light from the living room window. My 4 Plex apt was on a hill and overlooked the valley separated by hills that let to the Pacific Ocean. At first I thought it was a helicopter with it's search lights but there was no sound. It hovered just outside of the window maybe 50 above it, then slowly went over our building. I could follow the lights as they seemed to be scanning the hillside behind our building before coming back to the front and just hovering for about 10 seconds. Then it suddenly sped off like shot out of a canon, got just over the distant ridgeline then took and immediate right angle turn, darting behind Mt. Tamalpais. I immediately knew it was a UFO based on the speed and never a sound. I soon after heard rumors that other people saw it but UFO sightings then didn't get much press, especially if you wanted to avoid being laughed at. I was 14 so nobody would listen to me anyways. To my surprise, I cannot find any other documented sightings from that night. Bizarre. I don't recall the exact time, it was night and dark. I found the date by researching the show I was watching.