On November 25, 1998, a sentry patrolling the perimeter of the Morón de la Frontera Air Base near the city of Seville (Spain) at five o' clock in the morning was startled to hear a sound he likened to "steel plate being cut".
The sentry shouted a challenge; when no one responded, he loaded his rifle and fired two shots in the air, while letting loose the German Shepherd watchdog that accompanied him on his rounds. Almost immediately following the two loud reports, an entity described as a two meter tall "sort of person" emerged from the surrounding thicket.
According to Spanish researcher José Manuel García Bautista, the sentry was astonished by the being's height and its fluorescent green eyes, adding that the darkness kept him from making out its physical details. With his heart pounding, the sentry fired another shot straight into the creature, to no avail. He then ordered the German Shepherd to attack; the animal charged the dark figure, but stopped short of it with a loud whimper. The highly trained guard dog cowered back to the sentry, who was at a loss as to what to do next. The entity spared him further confusion by vanishing into the thicket once more.
After contacting his superiors over a handheld radio, the sentry was taken to see the base commander, who advised him to keep the whole affair confidential and awarded him a week's leave. But before going off on his furlough, the sentry noticed that his guard dog now sported a long scar running along its left shoulder blade: physical proof of the encounter with the unknown creature.
[From "The Humanoid Conspiracy" by Scott Corrales]