AURORA, Colorado, July 20: A gunman wearing a gas mask set off an unknown gas and fired into a crowded Colorado movie theater at a midnight opening of the latest Batman movie, killing at least 12 people and injuring at least 50, authorities said.
It was the worst mass shooting in the U.S. since the 2007 shooting on the Virginia Tech campus.
Some moviegoers said they thought the attack was part of the show. Then they saw a silhouette of a person in the smoke at the front of the theater, pointing a gun at the crowd.
Aurora Police respond to the Century 16 movie theatre early Friday morning, July 20, 2012. (AP)
"I told my friend, ´We´ve got to get out of here,´ but then he shot people trying to go out the exits," Jennifer Seeger told NBC´s "Today." She the shooter made his way up the aisle, shooting as he went, saying nothing.
Some of the injured were children, with the youngest a 3-month-old baby. Victims were being treated for chemical exposure apparently related to canisters thrown by the gunman. The shooter, a man in his 20s, was arrested shortly after the midnight attack near a car outside the multiplex theater in Aurora.
FBI spokesman Jason Pack said there was no indication in the investigation so far of any connection to terror groups.
President Barack Obama said he was saddened by the "horrific and tragic shooting."
It was the worst mass shooting in Colorado since the Columbine High School massacre in 1999, where two students opened fire and killed 12 classmates and a teacher.
Aurora police spokesman Frank Fania told ABC´s "Good Morning America" he didn´t know yet if all the injuries were gunshot wounds. He said some might have been caused by other things, such as shrapnel.
Police officers ran in and told people to leave the theater, Salina Jordan told the Denver Post newspaper. She said some police were carrying and dragging bodies.
The suspect was taken into custody, but no name was released. Aurora Police Chief Dan Oates said there was no evidence of other attackers. There was no immediate word of a motive.
"A gas mask, rifle, handgun at least one additional weapon (were) found," he said.
The suspect spoke of "possible explosives in his residence," Oates said. Police were at the Denver-area apartment and had evacuated the building´s other residents. Oates did not say whether explosives had been found.
He said police also checked for explosives at the theater and secured those areas.
Moviegoers spoke of their terror as violence erupted.
Benjamin Fernandez, 30, told the Post he heard a series of explosions. He said people ran from the theater and there were gunshots as police shouted "Get down!"
Jordan told the paper one girl was struck in the cheek and others in the stomach, including a girl who looked to be around 9.
Jordan said it sounded like firecrackers until someone ran into his neighboring theater yelling, "They´re shooting out here!"
KUSA-TV reported that some hospitalized victims were being treated for chemical exposure, related apparently to canisters thrown by gunman.
Aurora is home to a large Defense Department satellite intelligence operation at Buckley Air Force Base.