(MSNBC) -- New details have surfaced about the two alleged gunman who opened fire Sunday night outside of a "draw Muhammad" cartoon contest in Garland, Texas. A security guard on duty was wounded in the shooting. The two gunmen, who police say were armed with assault rifles, were shot and killed by a traffic cop on the scene, according to police.
The terror group known as the Islamic State of Iraq and Syria has claimed responsibility for the shooting in Garland, Texas, a suburb of Dallas.
Officials said about 200 people attended the heavily policed event at the Curtis Culwell Center in the Dallas suburb of Garland. As the event was drawing to a close, two gunmen armed with assault rifles drove up to the venue and began shooting, wounding school district security guard Bruce Joiner in his lower leg. Garland police officers returned fire, killing the men.