The FBI and Department of Homeland Security said on Saturday that ongoing investigations around reported drone sightings over New Jersey have found many reports are, in fact, manned aircraft. The FBI has been investigating hundreds of reports of drones operating at night since mid-November,

Officials sound alarm over reports of the strange sights—seen over New Jersey, New York, Maryland and Pennsylvania—with one asking for a “limited state of emergency.”

Dozens of witnesses have reported seeing drones in New Jersey starting in November. At first, the drones were spotted flying along the scenic Raritan River, a waterway that feeds the Round Valley Reservoir, the state’s largest aquifer, about 50 miles west of New York City.