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A horror movie filming in Holmesburg prison decided they needed some real prison guards to help out – and Philly correctional officers were more than happy to oblige.

“Death House” is an upcoming horror film set in an Area 51-esque government prison where “Hell literally breaks loose” during a prison break by prisoners led by an “occultist Neo-Nazi,” according to the film’s website.

It was first written by horror legend Gunnar Hansen, who played “Leatherface” in famed gorefest “The Texas Chainsaw Massacre,” but who recently passed away. The production continues however under director and writer Harrison Smith (director of “Camp Dread”) and features Danny Trejo (“Machete”).

In other words, it sounds like the best thing ever.

For guards working in the 100-year-oldprison, it was even better. Some of them got to serve asextras playing, well, prison guards – except in the hellish “Death House.”

“Death House is basically a prison from hell – like, actually hell,” said correctional officer Kelley Sellers, 45, who was one of the extras. “It was a wonderful experience, like nothing I ever experienced.”

Six guards played extras under the leadership of the prison’s “commander,” played by Kenny Ray Powell, during a day of shooting.

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Since they were basically playing themselves, they didn’t need any direction.

“We already have correctional experience doing the things they asked us to do, said correctional officer Jeffrey Bishop, 32. “They’d ask, ‘How would you handle this situation? You’re the correctional experts,’ and let us handle it.”

These guards were picked as a reward for their attendance records.

“They wanted guards as extras, and I realized I had just gotten the list of who had perfect attendance in 2015, so I knew who to pick,” said Philadelphia Prisons System spokeswoman Shawn Hawes.

#horrorfans what do u think of #DrFletcher Wanted to change up my look for my intense character in @DeathHouseMovie pic.twitter.com/rO74BiXCoA — Dee Wallace OFFICIAL (@Dee_Wallace) April 5, 2016

A long day #3 at #DeathHouse but we got it and the film is looking great! Kane Hodder arrives tomorrow! pic.twitter.com/Cq3g5EEnCt — Harrison Smith (@HarrisonSmith85) April 7, 2016

How’d they get into the mindset of prison guards amidst a demonic prison break? Well, it actually wasn’t that hard, they said.

“At any given moment, you know that anything can happen behind the walls,” Bishop said.

Sellers agreed: “We’re mentally prepared for anything on a daily basis. Thank god we don’t have to worry about getting suited up for anything like that.”

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Beyond getting a taste of acting, Sellers and Bishop said they also got tips of the trade from director Smith, as well as actress Dee Wallace, whose horror films have earned her a cult following.

“Dee Wallace, just to be able to sit and converse with her getting some advice from her if me or Officer Bishop was ever able to get into Hollywood or filming or anything like that was great,” Sellers said. “All the staff were wonderful. They just seemed normal like everyday people.”

Filming is expected to continue through April 26.

Hawes said she hopes to eventually screen the film in the prison.