BRISTOL, Tenn. (WJHL) – Police remain on alert after the FBI issued a warning about a new movie.

Social media posts discovered by police called for “mass shootings” related to Joker, which premiered on Thursday.

The concerns trace back the 2012 Colorado movie theater shooting, where a gunman killed 12 people during another movie called The Dark Knight Rises.

PREVIOUS STORY: Local drive-in theatre reminds movie-goers that no costumes will be allowed during ‘The Joker’ movie

One Tri-Cities drive-in is taking steps for protection.

“This is the first time this has ever happened on a movie,” said Twin City Drive-In Theatre owner Danny Warden.

After high anticipation for Warner Brothers’ Batman spin-off, Joker, social media posts discovered by police called for “mass shootings” related to the film.

The FBI issued a warning to movie theatres and goers, telling them to identify two escape routes and to “run, hide, fight” in an active shooting situation.

“If they figure they can save anybody’s life or prevent a shooting or something like that, then I’m glad that they’ve done it,” Warden said.

Danny Warden owns Twin City Drive-In Theatre in Bristol, Tennessee. He posted on Facebook that all costumes were banned this weekend.

“It’s just common sense I guess that something like this should be done,” Warden said.

Although it’s common for moviegoers to dress up for new releases featuring popular characters, those watching this weekend say they understand the concerns and are happy people are aware.

“It makes me feel a little bit safer and I understand with all the sensitivity,” moviegoer Neil Stout said. “We live in a new world than what it was years ago, you never had to think about things like this. But with the precautions put forward, I think it’s a good step for them to take.”

Although the movie was expected to be highly attended, numbers on Friday night’s showing were down for the drive-in.

“This movie has gotten such negative reviews that I think it’s what really hurt us,” said co-owner Ellen Warden. “People are just afraid that something would happen.”

Parents of those killed in the Aurora shooting have written letters to Warner Brothers asking it to help lobby for gun reform.