At least 12 people are dead, dozens more injured after an attack at a packed movie theater.
The man accused of unleashing a spray of gunfire on the unsuspecting moviegoers, 24-year-old James Holmes, is in custody, but the investigation into what provoked his attack is only just starting.
The movie theater was packed for a midnight showing of "The Dark Knight Rises," when authorities say Holmes propped open an exit door and threw in a smoke canister, before he opened fire.
Police say there was a lot of confusion after the first gunshots, because many people thought the sounds were coming from the screen.
“Everybody was running in the chaos and everything and he casually walks away from the screen like nothing happened. Honestly that is the part that really got me. The fact that a man can really just walk like nothing happened knowing that he just shot a whole bunch of people,” said witness Chris Ramos.
Police officers responded and found the gunman in the back of the theater outside of the parking lot, near a car with a gas mask and at least a rifle and a handgun.
When officers went to search his home for explosives, they discovered it was booby-trapped.
The suspect had no real criminal record and had recently dropped out of medical school.
New York City's Police Commissioner says he was briefed that the gunman painted his hair red and called himself 'The Joker,' the villain from the Batman movies.