Ongoing sightings of mysterious drones in the skies over New Jersey have sparked alarm among residents as officials continue to investigate the odd nightly incursions.

Although authorities maintain that the drones pose no apparent threat to the public, many questions remain about the mysterious objects, and their operators and ultimate purpose remain unknown.

This week, sightings of the small aircraft, which have reportedly been occurring over New Jersey now for several weeks, have extended into surrounding states, with recent observations occurring over Philadelphia, Pennsylvania and Brooklyn, New York.

In New Jersey, many of the recent sightings reported by residents have occurred in Morris County, home to the U.S. Army’s Picatinny Arsenal. One of the earliest known sightings of the New Jersey mystery drones occurred there on November 13, when a security officer was reportedly one of the first to have observed the objects.

Since then, at least ten more confirmed sightings have taken place near the arsenal, and seven more potential sightings remain unconfirmed.