(CBS4) – The Colorado Department of Public Safety sent ground crews to northeast Colorado Thursday night to investigate reports of drones in the area. Military and government agencies have denied any ties to the mystery drones, which have been spotted across Colorado and Nebraska.

(credit: CBS)

On Thursday night, CDPS identified three possible sightings, but two were eliminated as small aircraft and the third was suspected to be vehicle headlights. The operation covered an area spanning more than 1,200 square miles.

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The crews did not deploy their air resources because of heavy cloud cover. Officials said the investigative team did not receive any public reports of suspicious sightings to investigate.

The Colorado Division of Homeland Security & Emergency Management said there was a report of a drone coming in dangerous proximity to a medical helicopter on Wednesday evening. The drones reportedly have 6 foot wingspans, which makes investigators think they don’t belong to a hobbyist.

The Morgan County Sheriff’s Office is leading an investigation into the mystery drones with several sheriff’s departments in northeast Colorado. The FAA is also working with local law enforcement to identify the drone operator.

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(credit: CBS)

“I think we’re all asking ourselves that same question, we’ve asked the military, we’ve asked energy companies, we’re trying to find it out as well,” said Stan Hilkey, the executive director of the Department of Public Safety. “It is odd that nobody yet has been able to detect what it is.”

In a tweet Friday, Colorado’s Division of Homeland Security & Emergency Management said CDPS will continue to investigate reports of suspicious drone activity through the weekend. Any new data will be turned over to the Colorado Information Analysis Center.

There are several free resources to determine if a drone sighting is actually a commercial aircraft, including FlightAware, Plane Finder, the Air Traffic App, or asking your smartphone “what planes are above me right now?”

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The Department of Public Safety said the drone activity may not be in violation of any laws. If that is the case, they hope the operator using drones will come forward to help clear up the confusion.