If you witness a drone operation that appears dangerous or is being used to commit a crime please report it immediately to your local law enforcement first responders. They can protect public safety and can help discourage dangerous or illegal activities.
If you witness a drone not following FAA rules, you may reach out to your local FAA flight standards district office. The FAA's investigators may be able to investigate your report and follow up with the drone operator. Unauthorized drone operators may be subject to penalties and criminal charges.
Learn more about the FAA rules that must be followed while flying a drone within the National Airspace System: