RACHEL, Nevada -- Storm Area 51 is underway in Southern Nevada.
As many as 15,000 people are expected to descend on the tiny towns of Rachel and Hiko for special events celebrating the military research site.
RELATED: 'Storm Area 51' viral Facebook event attendees could face extreme temperatures, wild animals
Area 51 has long fueled fascination about extraterrestrial life, UFOs and conspiracy theories.
A 20-year-old college student created the Facebook event "Storm Area 51, They Can't Stop All of Us" over the summer as a joke, but more than 2 million people said they were going to the classified U.S. Air Force facility in Rachel, Nevada, to "see them aliens."
The military is taking the whole thing seriously.
The Air Force has issued stern warnings for people not to approach the Nevada Test and Training Range, where Area 51 is located.
Two Dutch Youtubers were arrested last week for allegedly trespassing near the highly restricted military site.
Military warning people to not approach Area 51 to 'see them aliens'