A British government official says a criminal investigation is underway after drones were spotted recently by the U.S. Air Force over English military bases

The drones were detected between Wednesday and Sunday, near Royal Air Force Lakenheath, Royal Air Force Mildenhall and Royal Air Force Feltwell, all three of which are in eastern England. The bases house thousands of U.S. service members, primarily Air Force personnel.

A number of unidentified drones have been spotted over three United States Air Force bases in England over the last six days, U.S. officials said on Tuesday. "Small unmanned aerial systems were spotted in the vicinity of and over RAF Lakenheath,