In “Triple 9”, a crew of dirty cops gets blackmailed by the Russian mob to execute a risky bank heist, and the only way to attempt the virtually impossible task is to manufacture a “999,” code for officer down. While shooting the film in Atlanta, the cast and crew — including stars Teresa Palmer, Gal Gadot, Anthony Mackie, Kate Winslet, Norman Reedus, Aaron Paul, Casey Affleck and Woody Harrelson — worked with real police and SWAT officers to ensure accuracy, Variety said.

“It was intense working with actual, organic police officers and SWAT to dictate what actually goes down on scene to scene,” actor Luis Da Silva Jr. told Variety at the Los Angeles premiere of “Triple 9” Tuesday. “It was intense. These guys are no joke.” Even before filming started, screenwriter Matt Cook sought advice from outside sources on how to pen a realistic and accurate story. He said he was first inspired to write “Triple 9” while on a road trip to Las Vegas “with a very good friend of mine who also happens to be a Phoenix police officer and works undercover in narcotics.” That friend, as well as others in the field, remained constant sources throughout the movie’s development.

Cook is a former Army veteran, and he had his first day of basic training on September 11, 2011. “I think an experience like that you draw from in every script you write,” Cook said. “I don’t think I would have the career I have, or be in the position like this, without the experience.”

Reedus shot “Triple 9” in Atlanta while also working on “The Walking Dead,” sometimes filming both projects on the same day. “(For) one, I would cover myself in blood and go fight for my life, and then the other one, I’d go slick my hair back and fight with a bunch of guys to rob people,” Reedus recounted.

Paul, who portrays a dirty cop in “Triple 9,” is no stranger to the bad guy role. “I love playing characters with a lot of conflict,” Paul said. “The very beginning of the film, you can tell he’s kind of an intense guy, and something very dramatic happens to him. He just continues down this very dark rabbit hole. For me it’s a lot of fun to play as an actor.”

Director John Hillcoat and cast members Affleck, Mackie, Palmer and Clifton Collins Jr. also attended the “Triple 9” premiere in downtown Los Angeles. After the screening, stars and guests headed up to the 24th floor of the Ritz-Carlton for an after party at WP24 by Wolfgang Puck. “Triple 9,” from Open Road Films, opens nationwide on Feb. 26.