Several dozen people - including a pilot, county constable and business owners - insist they have seen a large silent object with bright lights flying low and fast. Some reported seeing fighter jets chasing it.
"People wonder what in the world it is because this is the Bible Belt, and everyone is afraid it's the end of times," said Steve Allen, a freight company owner and pilot who said the object he saw last week was a mile long and half a mile wide. "It was positively, absolutely nothing from these parts."
While federal officials insist there's a logical explanation, locals swear that it was larger, quieter, faster and lower to the ground than an airplane. They also said the object's lights changed configuration, unlike those of a plane. People in several towns who reported seeing it over several weeks have offered similar descriptions of the object.
Machinist Ricky Sorrells said friends made fun of him when he told them he saw a flat, metallic object hovering about 300 feet over a pasture behind his Dublin home. But he decided to come forward after reading similar accounts in the Stephenville Empire-Tribune.
"You hear about big bass or big buck in the area, but this is a different deal," Sorrells said. "It feels good to hear that other people saw something, because that means I'm not crazy."
Sorrells said he's seen the object several times. He said he watched it through his rifle's telescopic lens and described it as very large and without seams, nuts or bolts.
Maj. Karl Lewis, a spokesman for the 301st Fighter Wing at the Joint Reserve Base Naval Air Station in Fort Worth, said no F-16s or other aircraft from his base were in the area the night of Jan. 8, when many sightings were reported.
Lewis said the object may have been an illusion caused by two commercial airplanes. Lights from the aircraft would seem unusually bright and may appear orange due to the setting sun.
"I'm 90 percent sure this was an airliner," Lewis said. "With the sun's angle, it can play tricks on you."
Officials at the region's two Air Force bases - Dyess in Abilene and Sheppard in Wichita Falls - also said none of their aircraft were in the area last week. The Air Force no longer investigates UFOs.
About 200 UFO sightings are reported each month, mostly in California, Colorado and Texas, according to the Mutual UFO Network, which plans to go to the 17,000-resident town of Stephenville to investigate.
Fourteen percent of Americans polled last year by The Associated Press and Ipsos say they have seen a UFO.
UFO sightings have been reported all over the world for centuries, including the infamous 1897 crash of a cigar-shaped object near the tiny Texas town of Aurora. While some thought it was a hoax, decades later investigators from UFO groups said evidence suggests the disfigured pilot's body buried that day was an alien.
In Chicago in late 2006, some United Airlines pilots and other employees reported seeing a saucer-shaped craft hovering over O'Hare Airport before shooting up through the clouds. But federal officials said nothing showed up on the radar and explained it as some type of weather phenomenon.
In 1997, dozens of people saw lights in a V-formation over Phoenix, a mystery that was captured on videotape and spurred calls for a government investigation. A few months later people reported a similar sight over Las Vegas.
One of the most famous cases was the 1947 crash on a ranch near Roswell, N.M. Although the government said it was a top-secret weather balloon, an Army officer who helped recover the debris came forward 30 years later claiming a cover-up, asserting that an alien spacecraft had crashed. Reports later surfaced that a base nurse told someone that autopsies were performed on aliens from the wreckage.
A few months after the New Mexico incident the U.S. Air Force started Project Blue Book, which investigated more than 12,600 reported UFO sightings - including 700 that were never explained - before the program ended in 1969.
Erath County Constable Lee Roy Gaitan, who said he isn't sure about the existence of UFOs, said one night last week he first saw red glowing lights and then white flashing lights moving rapidly across the sky.
"I didn't see a flying saucer and I don't know what it was, but it wasn't an airplane and I've never seen anything like it," Gaitan said. "I think it must be some kind of military craft - at least I hope it was."