Lucerne, Colorado — The FBI, FAA and U.S. Air Force are investigating a mystery in the skies over Colorado, Nebraska and Kansas. Swarms of drones have been spotted there — sometimes in formation. But who's flying them?

For the last week, Michelle Eckert has spotted a high-flying, night-time mystery above her rural northern Colorado home. She has seen drones, sometimes a dozen or more with wingspans 6 feet wide.

"The sky is lit up with Christmas lights basically," she told CBS News. "There's lights and things flying all over. It reminded me of something from a movie."

Sheriff's departments across the border area of three states have been flooded with at least 30 reports since mid-December.

"I think whomever is responsible for it will probably have some answering to do to the general public," Sheriff Steve Reams of Weld County, Colorado, said.

On Monday, dozens of agencies met and established a task force with the FBI, FAA and the Air Force. But they're no closer to an answer. The military and local companies have denied responsibility.

CBS News waited with Eckert until the sun went down — and the skies lit up.

Drone sightings are startling residents in three states. CBS News

It was only dark for half an hour and drones could be seen all over the sky and appear as twinkling lights; sometimes just one, but other times there were clusters of six or more.

There are still more questions than answers and residents are feeling vulnerable.

"It feels like an invasion of privacy almost," Eckert explained.

Late Monday, one of the sheriff's offices announced they were looking for a closed box trailer with antennas or a large suspicious van. They asked anyone who has spotted it to call authorities.