LOS ANGELES — “Without question, working on this film was a constant rush,” said Aaron Paul, chatting up his movie “Triple 9,” opening Friday. Directed by John Hillcoat (“The Road,” “The Proposition,” “Lawless”), the film is about an unscrupulous group of corrupt police officers in Atlanta who team up with a vicious gang of criminals to plan the killing of a fellow police officer.

The title of the movie refers to a police code — “999” — indicating an officer is down. The theory behind this criminal act was that the broadcast of a triple 9 call would direct police away from a huge bank robbery in another part of town.

Talking about the film’s 10-minute opening sequence — the very violent attack on the bank — Paul smiled as he said, “It was every actor’s dream. Non-stop movement, masks, guns, shooting everywhere. It was crazy! I loved it!”

Norman Reedus, best known for his role as Daryl Dixon in “The Walking Dead,” agreed with Paul: “We never had a moment when we weren’t having an absolute blast.” In the film, Paul portrays a strung-out ex-cop and Reedus is an ex-Special Forces operative who has turned mercenary and is part of the team forced by the gangsters to pull off this violent crime.

The gang is led by Kate Winslet, and both Paul and Reedus said they couldn’t believe how she transformed herself for the movie. “Kate is truly almost unrecognizable,” said Reedus. “That big hair, that crazy Israeli-Russian accent … the whole way she presented herself was amazing. But, of course, that’s why she’s the actress she is.”

Paul added, “She was so brilliant and frankly pretty scary! She was a total badass!”

The all-star cast also includes Casey Affleck, Woody Harrelson, Anthony Mackie and Chiwetel Ejiofor. In a separate interview, Mackie (who plays a crooked cop) and Ejiofor (another ex-Special Ops veteran) talked about how they prepared to play the bad guys in this film that is basically chock-full of bad guys.

“I guess we all wanted to ‘out-bad’ each other,” said Mackie with a chuckle. As for Ejiofor, the hardest part “wasn’t the actual acting, but all the preparation I had to do to be convincing as a guy who would have had plenty of killing experience. … That involved much more time than I would have liked in the gym pumping weights, plus some really good time spent training with former Navy SEALs.”

Playing another of the corrupt cops is Clifton Collins Jr., who has a history of playing guys on the dark side. But the concept of being “a bad guy” is not something the actor incorporates when he approaches a role.

“You have to remember, so-called bad guys never think of themselves as bad. Sure, they do bad things, but they always have a rationalization for that. … Of course, in many cases, those characters are just plain scary crazy!”