When Jake Gyllenhaal gets into character, he really gets into character! While working on the set of his new film, Nightcrawler, Gyllenhaal punched his hand into a mirror so hard that he had be taken to the emergency room.

“Jake flipped out,” a Nightcrawler source told PEOPLE. “His character was looking into a mirror during the scene and punched the mirror in anger and broke it, cutting himself so bad he had to be taken to a hospital.”

The source adds that there were no issues on set that day that caused him to punch the mirror. He was simply filming an intense scene, and got wrapped up in the heat of the moment.

“The scene was emotionally charged and his character was talking into a mirror and he got so into it, he banged his hands against the mirror and it broke and cut him,” the source close to Gyllenhaal says. “It was all the scene and not because he was mad about anything else.”

The source confirmed that Gyllenhaal was taken to the hospital to receive stitches, but was able to return to the set later that day. Gyllenhaal plays a crime-scene reporter in the film, and had to lose 20 pounds for his character. The film also stars Rene Russo and Bill Paxton, and is set to release in 2014.

US Weekly got a chance to talk to Gyllenhaal at the 17th Annual Hollywood Film Festival in October. He described why he chose to work so hard to lose the weight to get into character. “I knew that [Lou] was literally and figuratively hungry,” he said. “So I was always a bit hungry. I just love this movie. That’s how I did it. There really was no technique.”

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