Drones, with at least a six-foot wingspan, are seen nightly in Yuma and Phillips County, Colorado

The Phillips County Sheriff's Office said it is investigating the 17 drones, which 'though startling, are not malicious in nature'

The drones are spotted around 7pm and disappear by 10pm each night

They are usually seen hovering approximately 200 to 300 feet above the ground

The sheriff's office said based on the size and amount of drones that it's not likely operated by hobbyists

At least 17 mysterious large drones have been spotted flying search patterns over Colorado every night - but baffled authorities can't explain where they are from or who is flying them.

The drones, with estimated six-foot wingspans, have been seen in the sky over Phillips and Yuma counties each night for at least a week.

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Phillips County Sheriff Thomas Elliott said the drones hover between 200 feet and 300 feet off the ground in search patterns taking up approximately 25 miles.

He said there are at least 17 large drones which appear each evening around 7pm, and generally disappear about three hours later.

That size and amount of the hovering overhead would appear to rule out hobbyists, Undersheriff William Myers told the Denver Post.

Stock photo of a random drone as residents in two Colorado counties have noticed drones in recent nights but federal authorities said it's not one theirs

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'If any of these drones fly onto your property or are looking into windows, please call the communications center immediately,' the Phillips County Sheriff's Office posted on its Facebook page Saturday.

Only one drone got close to see through a window, KUSA reported.

Still, the sheriff's office will investigate all calls and conduct a forensic evaluation to determine who owns the drones. They are following up on all leads and communications with state and federal agencies to pinpoint the exact nature to their activities.

But, Phillips County sheriffs are not overly concerned.

'We believe that the drones, though startling, are not malicious in nature,' they added on Facebook.

Jackson County in Colorado, as communities have been seeing drones each night for more than a week and law enforcement has not determined who is operating them

The drones are too quiet to hear from the ground, but the white strobe lights can be seen from street level, along with red, blue and green lights.

Myers told the Denver Post that he watched eight of the drones head across the Yuma County border at the intersection of U.S. 385 and County Road 54.

He said that at the same time, another drone remained stationary, hovering about 25 miles away over the town of Paoli.

The sheriff's office said one person was chasing a drone while doing 50 miles per hour in his vehicle, but lost it when he ran out of gas.

While sheriffs don't know who's operating them, they do know it's not the federal government.

A stock photo of a drone over a mountain at dusk, as sheriffs in parts of Colorado are dealing with a more than unknown drones at night for more than a week

The Federal Aviation Administration had no information on the drones, while the Air Force said it is not one of theirs, the Denver Post said.

The Drug Enforcement Agency also told the newspaper that the drones don't belong to the agency.

Even if the sheriff's office does get an identification, those responsible may not face any criminal charges.

'The way Colorado law is written, none of the statutes fit for harassment or trespassing,' Myers told the Denver Post.

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'Colorado hasn't gotten on board with identifying the airspace around your property as the actual premises, so we don't have anything we could charge.'