UFO Sighting in San Juan, San Juan Province on July 31st 1973 – small saucer hovrring above building for 5 minutes then took off

In the year 1973 I was traveling in my vehicle from Levittown to San Juan, Puerto Rico. I saw a bunch of vehicles stopped on the side of the road. So I also stopped to see what was happening. There was a small flying saucer hovering above a cement pipe factory. It was metallic in color , had a dome, I counted five portholes. As it was hovering there were different colored lights coming out of the portholes as there was something spinning in the center of the craft. After a few minutes whatever was spinning in the center of the craft sped up and the lights turned to a golden bright color and the craft shot into the sky and disappeared.