An Army blimp broke loose from its mooring at Aberdeen Proving Grounds in Maryland around noon and is now being tracked by two U.S. fighter jets, the Pentagon said Wednesday.
The blimp has one cable hanging from it, which U.S. authorities are warning people to stay away from, according to North American Aerospace Defense Command spokesman Navy Lt. Joe Nawrocki.
Nawrocki said he is "99 percent sure” the blimp is going to come down in Pennsylvania, and not cross into New York.
The device was at one point traveling 16,000 feet above central Pennsylvania at around 30 miles per hour, but has lost altitude and speed since then, he said.
Nawrocki said the blimp is "much closer to the ground right now," but did not want to estimate how close.
The Federal Aviation Administration is aware of the loose blimp, and two F-16 fighter jets from Atlantic City Air National Guard Base are monitoring it.
The U.S. military has also contacted local Pennsylvanian authorities and is working with the police and National Guard to maintain control of the device, which could contain secret data.
The untethered device is part of what's known as a JLENS, or Joint Land Attack Cruise Missile Defense Elevated Netted Sensor System. It consists of two aerostats that float 10,000 feet in the air and carry powerful radars that detect airborne threats. The system is manufactured by Raytheon.
Defense Secretary Ashton Carter said the U.S. would "get it to descend" but did not elaborate on how.
Air traffic officials are working to ensure the blimp does not interfere with any flights.
"NORAD officials are working closely with the FAA to ensure air traffic safety, as well as with our other interagency partners to address the safe recovery of the aerostat," a NORAD statement said.
— This story was updated at 3:31 p.m.