Department of Homeland Security Secretary Alejandro Mayorkas offered a possible explanation for the recent uptick of drone encounters along the eastern seaboard—particularly in the skies above New Jersey—which have prompted concern among residents and lawmakers.

The FBI is among several agencies investigating and has asked residents to share videos, photos and other information they may have about the drones.

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.”