MUNCY, Pa. — A slow-moving, unmanned Army surveillance blimp floated over Pennsylvania for hours causing electrical outages as its tether hit power lines, after it broke loose from its mooring at a Maryland military facility.

The 240-foot helium-filled blimp, which had two fighter jets on its tail, came down in at least two pieces Wednesday near Muncy, a small town about 80 miles north of Harrisburg, the state capital.