The 31-year-old, who appeared in 2005 film 'Sin City', is set to reprise her role as Nancy Callahan, a dancer who gets mixed up in the criminal underworld.
Alba said she has been enjoying target practice at a firing range in California. She posted a picture on Twitter showing her holding a gun and smiling as she posed for the camera, reports contactmusic.com. In a message alongside the picture, she posted: "What a way to start the day. Training for a movie is sort of fun."