As the day of “Storm Area 51” arrived, a motley group of about 100 “alien-chasers” converged on the back gate of the secret site early Friday, according to the Las Vegas Review-Journal. At least two people were reportedly detained by local sheriff's deputies.

“Storm Area 51” became a viral phenomenon after a joke Facebook post in July urged people to crash the military base “to see them aliens.” Conspiracy theories surrounding extraterrestrials have long swirled around Area 51. Originally scheduled for 3 a.m. PDT Friday, “Storm Area 51” garnered global attention, as well as security concerns.

The Review-Journal reported that about a dozen officers were stationed at the gate on the outskirts of Rachel in Lincoln County, Nevada, and were joined by an officer with a police dog at 3 a.m. PDT. The mood was mostly lighthearted, according to the Review-Journal, as officers joked with the crowd. “The Final Countdown” blared out from a speaker brought to the gathering.

'STORM AREA 51' RAID BRINGS ALIEN 'COMMUNITY OF BELIEVERS' TO NEVADA DESERT

Images tweeted by Review-Journal journalist Mick Ackers showed one man wearing what appears to be a tinfoil hat and another in an astronaut costume. One attendee is pictured brandishing a North Korean flag.

'STORM AREA 51': STRANGE TIMES OUT ON THE 'EXTRATERRESTRIAL HIGHWAY'

The Associated Press reported that at least two people were detained at the gathering. Authorities said one person was arrested on a charge of public urination and another was detained early Friday.

Gerard Ramalho, a news anchor for News 3 Las Vegas, tweeted that a woman was detained when she tried to enter the restricted area. “One woman in her 20s tried to cross, but was detained,” he tweeted.

In neighboring Nye County, authorities say about 40 people gathered overnight at Area 51 with plans to storm the gates before leaving peacefully. The Nye County Sheriff's Office said in a video news release Friday that the group initially came together outside the Area 51 Alien Center in Amargosa Valley about 3 a.m.

Authorities say some of the people then went closer to the gates before they left after "heated warnings" from officers. Everyone was gone by 5 a.m. They were described as being compliant and peaceful.

The Air Force has issued stern warnings for people not to try to enter the Nevada Test and Training Range, where Area 51 is located.

'STORM AREA 51': TAKE A PEEK AT THE MYSTERIOUS SITE’S ENTRANCE

The security site covers an area almost the size of the state of Rhode Island. It is separate but adjacent to the Nevada Test and Training Range, an area almost twice the size of Delaware, where the Air Force conducts training in aerial combat and bombing and tests stealth aircraft. Access to Area 51 is strictly prohibited.

Deputies in Nye County, Nevada last week arrested two Dutch tourists attracted by "Storm Area 51." The men pleaded guilty to trespassing at a secure U.S. site nowhere near Area 51 and were sentenced to three days in jail after promising to pay nearly $2,300 each in fines.

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Fox News’ Travis Fedschun, Chris Ciaccia and the Associated Press contributed to this article. Follow James Rogers on Twitter @jamesjrogers