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WASHINGTON COUNTY, Colo.  –Law enforcement officials in at least 4 Colorado counties are looking for the source of some mysterious drone sightings.

Sheriffs in Phillips, Lincoln, Yuma, and Washington Counties all confirm unusual sightings over the past week.

In most cases, those drones have been flying in formations, between 6-10 P.M., according to Washington County Sheriff Jon Stivers.

“I had reports of anywhere from 6 to 12,” he says. “One person believed it to more than 12, close to 30. It seemed like several of them were flying together, in 3 or 4 pairs,”

Stivers says those reports were just South of Highway 34, between Otis and Akron.

The Phillips County Sheriff was the first to report the sightings, confirming 16 drones in a Dec. 20 Facebook post.

Lincoln County later confirmed a single sighting in a post.

Sheriff Stivers says at this point, he does not believe the operations are malicious.

“I have no reason to think that, but it would be sure be nice to know what they’re doing.”

Drone Instructor Angel Andres Rosado says it’s likely a company performing some sort of mapping.

“When you hear one drone, somebody just got a new toy for Christmas and they don’t quite know the rules yet,” he says. “But when you hear 12 and they’re flying in formation? Someone’s doing some professional work out there, that’s my personal opinion anyway.”

Rosado says in certain cases, it can be beneficial to fly at night.

“At night particularly, you can load up a drone with a special sensor on the front that can actually use infrared technology to search for gas line leaks and perhaps other kinds of data like that,” he says. “So it’s completely possible there’s some company out there doing some sort of night infrared imagery perhaps. And they’re using multiple drones to get themselves a higher resolution, a clearer picture, of what they’re looking for.”

He says the company performing the operations would need special waivers to do it at night, and to fly in formation.

“If there’s 10 or 12 of them flying together, unless they have 10 or 12 drone operators, one for each one, they would require a special type of waiver to conduct that type of waiver,” he says. “I would imagine that level of sophistication, to even control 12 drones at one time, requires some pretty advanced technology, some pretty smart people to do that. I would imagine, and I would hope, they’re doing it legally.”

He says with proper waivers, the company would not be required to notify the FAA before every flight.

“When you get a night waiver it basically just means you have permission to fly the drone within certain stipulations but it usually doesn’t require you to notify the FAA of every single flight,” says Rosado.

The FAA says they have “No FAA drone reports in Colorado matching this location or description.” They declined to answer further questions, referring FOX31 to military media relations.

We’ve reached out to the Air Force, and will update this article when we receive a response.