Authorities have confirmed reports of drone sightings in three more counties in northeast Colorado and at least one Nebraska county after nighttime drone flights in the region caused a national stir earlier this week.

The Denver Post reported Friday that clusters of drones flying at night have remained a mystery to local law enforcement officials and residents seeking to learn the identities of the operators and the purpose of the flights.

Authorities say the drones reportedly have 6-foot wingspans and fly in grid-like patterns in groups of six to 10.

Federal aviation, law enforcement and military officials say they do not have information about the aircraft.

Neither does the Phillips County Colorado Sheriff's Department in any mystery-solving sense but the deputies know the drones are up there. They've seen them.

In a December 20th Facebook post the department noted, "Deputies were out all night this evening along with Yuma County SO tracking these drones. Tonight we tracked over 16 drones between the two counties. We believe that the drones, though startling, are not malicious in nature."