Around 100 people gathered at the entrance to the secretive US military base before dispersing peacefully. More than 2 million people had originally answered the "Storm Area 51" Facebook event.
Alien enthusiasts from around the world converged on the entrance gate to Area 51 on Thursday. Many of the revelers wore alien masks and tin foil hats as they gathered for a Facebook event to "see them aliens."
The "Storm Area 51" event quickly went viral when it was posted in June, attracting more than 2 million would-be attendees. "They can't stop all of us," the post read.
But none of those in attendance on Thursday attempted to breach the gates of the heavily guarded military facility, located in the remote Nevada desert roughly two-and-a-half hours' drive north of Las Vegas.
A Canadian man was cited for indecent exposure, while another woman was briefly detained when she attempted to pass under a gate.
The attendees then left to join alien-themed festivals inspired by the Facebook event in the nearby towns of Rachel and Hiko.
Read more: Conspiracies are 'always theories of power'
Area 51 has long been central to UFO conspiracy theories. The US government only formally acknowledged its existence in 2013.
The military issued a warning ahead of Friday's event, saying that anyone who tried to trespass at the facility would face lethal force.
dr/kl (AP, AFP)