DOUGLAS COUNTY, Colo. — Colorado’s drone mystery is expanding.

The mysterious aircraft are now being spotted on the outskirts of metro Denver. Dozens of Castle Rock and Parker residents have reported seeing the large drones hovering over their cities for the past several days.

Additionally, a handful of Fort Collins residents have reported large numbers of drones over that city.

“They were like four to five feet, just all blinking lights,” said Scott LiCausi, a Castle Rock resident who has spotted the drones from his backyard two different nights.

Castle Rock resident Brian Toomey sent FOX31 cellphone video of the drones. He estimates they were at least six feet across.

“It’s interesting. Someone’s looking at something,” Toomey said.

Jim and Patti Thewes were driving home from dinner when they saw the aircraft.

“You could see them. There were four of them, perfectly spaced,” Jim said.

All of Castle Rock residents who spoke with FOX31 say the drones were large, but clearly not airplanes or helicopters. Many are a bit unnerved by what they saw, now wanting to know who is operating the drones.

“I don’t understand why they don’t want the public to know unless there’s something hidden,” said Jim Thewes.

“The fact that no one is jumping on it from the government, the FAA doesn’t seem concerned, it’s got to be the government,” added his wife Patti.