A massive US surveillance blimp that broke loose from its mooring, sparking power outages as it drifted around Pennsylvania dragging a 2000m cable has eventually come down to earth.
Two US F-16s fighter jets were scrambled to pursue the so-called JLENS blimp as it floated north of Washington at an altitude of about 4600 metres.
The North American Aerospace Defense Command (NORAD) said the huge balloon-like structure finally landed in Montour County in Pennsylvania. A military recovery team was en route to collect the runaway aircraft.
NORAD spokesman Captain Scott Miller said a section of the aerostat's tail had broken off and plummeted to the ground. It wasn't immediately known if it caused any damage or injuries.
Authorities warned people to "remain clear" as power blackouts were reported in the town of Bloomsburg, Pennsylvania.
Local television said the cable attached to the helium-filled blimp had been "hitting power lines and causing blackouts" in Bloomsburg.
It came untethered from its mooring at Aberdeen Proving Grounds, an army installation in Maryland about 120km northeast of Washington.
"People are warned to keep a safe distance from the airship and tether as contact with them may present significant danger," a statement from the Aberdeen Proving Ground said.
The two F-16s that monitored the blimp were armed but "were never looking seriously at shooting [it] down", Miller said.
The aircraft was equipped with an auto-deflation system but it was not known if that had deployed.
JLENS blimps carry powerful radars that can monitor an area about the size of Texas for airborne threats including unmanned aircraft, cruise missiles and other objects.