People claim they have seen large groups of drones flying through the night sky across rural areas of the United States. Their mysterious appearance has raised questions and launched an investigation. Officials in the western state of Colorado say they have found nothing unusual or criminal about the drones. They were mostly operated for personal enjoyment, commercial purposes, or weather-related events. But the investigation that followed the drones in Colorado with sightings into Wyoming and Nebraska will not ease the minds of many people. Theories about drones said to be as big as cars, flying in organized groups at night continue to spread.