Jake Gyllenhaal was briefly hospitalized after punching a mirror on the set of his new movie Nightcrawler on Wednesday morning (November 13, 2013). The actor lost 20 pounds to play a crime reporter in the movie and was deep in character when he injured his hand.

Jake Gyllenhaal Jake Gyllenhaal Plays A Los Angeles Crime Reporter in 'Nightcrawler'

"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," a source told People magazine.

Gyllenhaal was treated in the emergency room for a bunch of stitches, though quickly returned to work and was acting again within hours. 

Nightcrawler - Dan Gilroy's movie set for release next year -  follows the story of a driven young man who discovers the nocturnal world of Los Angeles freelance crime journalism. Gyllenhaal lost 20 pounds for the role and appears gaunt in our photos from the Nightcrawler set.

Speaking to Us Weekly at the 17th Annual Hollywood Film Awards, Gyllenhaal explained the reasoning behind the weight loss. 

"It takes place...in a land where I think there is a desert in a lot of ways, great opulence, and at the same time, great vastness and emptiness.I knew that [Lou] was literally and figuratively hungry," adding that he's emulating his character by getting into a "mode where I was always a bit hungry." 

Nightcrawler, which co-stars Bill Paxton and Rene Russo, was shot "on a 24-hour schedule" and with "no money, according to Gyllenhaal, who added "But it's a really solid screenplay."

Next page: our on-set pictures from the Nightcrawler set.