Gunman kills 12 at midnight showing of 'The Dark Knight Rises' near Denver

Twelve people were killed and about 50 injured when a gunman wearing a gas mask interrupted a midnight showing of "The Dark Knight Rises" near Denver today, police said.

Aurora Police Chief Dan Oates told KUSA-TV Channel 9 at a press conference at 3:15 a.m. local time that the gunman is in police custody and they do not believe there is any other shooter involved.

At about 12:30 a.m., the gunman appeared at Century 16 theater at the Town Center at Aurora and released a gas canister in theater 9, Oates said. Witnesses heard a hissing sound and gas emerged, and then the gunman opened fire, Oates said.

Police officers found the gunman behind the theater in a parking lot in possession of a gas mask, a rifle and a handgun, and another weapon inside his vehicle, Oates said.

Police found 10 dead in the theater and four others died at hospitals, while about 50 are injured, Oates said.

The gunman "made statements of possible explosives in possession at his residence" and police have evacuated his apartment building in northern Aurora and are checking for explosives, Oates said. Police are also looking for other explosives in the parking area, he said.

"This is a horrific event," Oates said. "Our hearts go out to the families. We have mobilized the witnesses we could get our hands on to an area high school."

The FBI is working on the investigation jointly with Aurora police, said James Yacone, the special agent in charge for Colorado and Wyoming.

"We have a significant amount of investigators that have responded and are working shoulder to shoulder with the Aurora Police Department at this time," Yacone said. "What we're doing is really asking for the assistance of the public at this time. We need to talk to any potential witnesses."

Aurora's Century 16 had three theaters with midnight showings of the Batman movie "The Dark Knight Rises" that were attended by a festive audience including many dressed in costume, witnesses told KUSA-TV. The city is located about 10 miles east of Denver.

About 15 minutes into the early Friday morning film, witnesses heard a "boom" and then the rapid spatter of gunshots.

Patrons fled screaming and crying as the gunman continued to shoot. Witnesses said bullets penetrated the wall and entered the adjoining theater also showing "The Dark Knight Rises."

Clarification: Police originally put the death toll at 14. That number has since been revised to 12.