DENVER — Several people living along Colorado’s eastern Plains have spotted large-scale drones flying over their communities late at night. No one knows who owns them or what the drones are being used for.

The F.A.A. is currently investigating the situation. Drones have been spotted above Sterling, Fort Morgan, Brush, Wray and several other towns in northeast Colorado.

“My best guess would be they’re doing some sort of surveying,” said Joe Celestino, chief operating officer of Vertigo Drones in Rochester, New York.

Celestino and his colleague Amanda Saul both have experience with large-scale drones. Eyewitnesses living in the affected communities describe the drones as ‘huge,’ with wing spans as long as 6 to 7 feet.

According to Celestino, drones that size are strong.

“Extremely powerful,” he said. “And they can fly at hours at a time too”.

The drones have been appearing at night. While no one is sure why, Celestino and Saul have a theory:

“If it’s at night and they’re flying, it’s probably thermal related,” Celestino said.

“Some inspections are done at nighttime just because with the FAA, you can’t fly over people. So depending on where they are, they might be using nighttime waivers to avoid that aspect of that,” Saul added.

Large-scale drones could cost between $30,000-$40,000.

Celestino believes they either belong to the military or to a multi-million-dollar company.

The Problem Solvers are continuing to investigate this situation.