Two gunmen were killed and a security guard wounded in an attack outside a controversial Dallas-area event Sunday evening where organizers were holding a contest for cartoons featuring the Muslim prophet Muhammad, police said. The shooting in Garland, a Texas suburb about 20 miles from Dallas, was preceded by messages from two social media accounts that supported extremist Islamic viewpoints. One tweet, sent at 6:35 p.m., used the hashtag "#texasattack." The user wrote, “May Allah accept us as mujahideen.” Attendees inside the conference didn’t get word about the shooting until 6:50 p.m. -snip- Two social media accounts tweeted messages about...