David Becker / Getty Images

A Facebook event for a raid on Area 51, a classified military base in Nevada, is back online after being mistakenly removed. Event creator Matty Roberts received a notice that the event had been removed for violating Facebook's community standards, according to a screenshot he posted Saturday.

A Facebook representative said the removal was a mistake and the page is now available again.

More than 2 million people have indicated they're attending the Sept. 20 event, called Storm Area 51, They Can't Stop All of Us. Another 1.4 million have marked that they're interested.

The event's description lays out the plan: "We will all meet up in rural Nevada and coordinate our parties. If we naruto run, we can move faster than their bullets. Lets see them aliens."

Area 51 is a highly classified zone about 150 miles from Las Vegas. It's not clear what the base is used for, though there's speculation it's a location for aircraft development. Area 51 has therefore become associated with alien conspiracies, involving everything from alien spaceships to aliens themselves, which are allegedly housed within the classified zone.

The US Air Force has strongly advised against storming the area, telling The Washington Post that it "always stands ready to protect America and its assets."

Originally published Aug. 6 at 1:49 p.m. PT.

Update, 1:58 p.m. PT: Adds additional background.