This is why you get permits: US university lockdown triggered by...

A campus lockdown at Arkansas State University Sunday was such a big story, it even became the subject of an RT Breaking News alert.

READ MORE: Arkansas State University on brief lockdown after reports of gunmen on campus

Well, turns out the three male students dressed in black and carrying guns that - surprise, surprise - caused a frenzied reaction were just characters in a student movie shooting on campus.

The school was already on edge after a real lockdown and evacuation in December when an armed man had a stand-off with police before being captured.

The students will not face criminal charges, but university spokesman Bill Smith said they would face a disciplinary review at the school.

“Obviously we encourage people, if they see something out of the ordinary, to say something,” Smith told AP. “But if you are going to be doing something that might be construed as being out of the ordinary, that you probably need to check in with the university administration to let us know what you're doing.”

Shortly after 1:45 p.m. Sunday, students were alerted to a lockdown on campus after reports of gunmen in the area.

The lockdown lasted 50 minutes while police were alerted to the situation.

According to a university news release, police quickly determined the gunmen were costumed students and posed no threat.

Hilariously, a couple of tweeters used the fake lockdown to make real statements about gun control.

ASU’s December standoff with 47-year-old Brad Bartelt happened after he drove a truck onto the campus lawn and doused it in gasoline.

He was carrying a shotgun, but surrendered to police without firing a shot.