A gunman armed with three weapons, including a rifle, opened fire in a theater crowded with families and children at a midnight showing of the Batman movie The Dark Knight Rises in a Denver suburb early Friday morning, killing at least 12 people and wounding at least 38 others, the local police and federal officials said. Multimedia Slide Show 12 Dead in Colorado Theater Shooting Related The Lede Blog: Live Updates on Movie Theater Shooting in Colorado (July 20, 2012) Connect With Us on Twitter Follow @NYTNational for breaking news and headlines. Twitter List: Reporters and Editors Enlarge This Image Karl Gehring/The Denver Post, via Associated Press People gathered outside the Century 16 movie theater in Aurora, Colo., on Friday. More Photos » Enlarge This Image Ed Andrieski/Associated Press Police outside the theater in Aurora on Friday. More Photos » The New York Times Click for a more detailed map of the site of the shooting in Aurora, Colo. More Photos » Readers Comments Share your thoughts. Post a Comment » Read All Comments (199) » Just before he began shooting, the police said the man, identified as James Holmes, believed to be 24 years old, had walked to the front of the packed theater in Aurora, Colo., and set off a smoke device before firing into the audience. Mr. Holmes was arrested in a parking lot behind the theater near his car without further incident, according to the Aurora Police. He had a gas mask and was armed with at least one rifle and a handgun. A third weapon was found inside the theater. The authorities believe Mr. Holmes had acted alone and that the death toll may increase because some of the wounded were seriously injured. Were treating this as an active shooter investigation working with Aurora police, according to a statement released by the Federal Bureau of Investigation. No indications at this early point in the investigation of any nexus to terrorism. After his arrest, Mr. Holmes told the police that he had explosives at his Aurora residence. The F.B.I. and local police have evacuated the area around an apartment building in Aurora as they check for explosive devices inside an apartment, the authorities said. The shooting erupted at the Century 16 Movie Theater, during the first showings of The Dark Knight Rises. Throngs had gathered, some dressed as characters from the highly anticipated Batman sequel. Witnesses said the gunman appeared to have entered the theater through an exit door and described smelling either pepper spray or tear gas in the theater as the gunfire rang out. Dan Oates, Auroras police chief, said that the smoke device had made a hissing sound before starting to emit smoke. President Obama, who spent the night in southern Florida as part of a campaign swing, was notified of the shooting by his top counterterrorism adviser, John O. Brennan, at 5:26 a.m., according to the White House. He later released a statement saying that he and the first lady were shocked and saddened by the horrific and tragic shooting in Colorado, and vowed to bring those responsible to justice. As we do when confronted by moments of darkness and challenge, we must now come together as one American family, Mr. Obama said. All of us must have the people of Aurora in our thoughts and prayers as they confront the loss of family, friends and neighbors, and we must stand together with them in the challenging hours and days to come. Mr. Obama will return to Washington on Friday afternoon, cutting short his Florida trip, his campaign said. Colorado television showed several ambulances moving about and dozens of police officers gathered at the Century 16 movie complex in the early morning darkness. A police robot could be seen inspecting a white compact sedan, its two doors and trunk wide open, in the parking lot of the movie complex, television images showed, though it was unclear whether the car belonged to the gunman. I saw a man walk in through the exit, a witness told a reporter from 9NEWS in Colorado, saying he threw what appeared to be a pair of gas canisters to the ground. He waited for both the bombs to explode before he did anything. Then, after both of them exploded, he began to shoot. Cellphone video appeared to show the traumatic scene outside of the large multiplex immediately after the shooting. Some people wandered away with bloodstained shirts as others could be heard screaming, Get out of here! A witness told CNN affiliate KUSA that he was in one of the other theaters showing the movie. Its crazy to think I could have been in the other line, he said. We were watching a scene of the movie it was a shootout scene, there were guns firing, he said. Then loud bangs came from the right of the theater. Smoke took over the entire theater, and it was really thick and no one could really see anything. Me and my sister were sitting there wondering what was going on. Five people were limping, wounded, slightly bloody. I saw a girl who was pretty much covered in blood. It made me think the worst, the man said. A cop came walking through the front door before everyone was cleared up and before everything was completely under control holding a little girl in his arms, and she wasnt moving.