12 Dead After Gunman Opens Fire at Midnight Showing of New Batman Movie in Colo.

UPDATE:

The shooter is reportedly 24-year-old James Holmes. You can read our separate story on those developments here.

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AURORA, Colo. (The Blaze/AP) -- A gunman wearing a gas mask set off an unknown gas and fired into a crowded movie theater in suburban Denver at a midnight opening of the Batman movie "The Dark Knight Rises," killing 12* people and injuring at least 50 others, authorities said.

The violent and chaotic scene erupted about 12:30 a.m. MDT as a gunman stood at the front of one of the Century 16 theaters at the Aurora Mall where the latest Batman movie "The Dark Knight Rises" was playing, police said.

"Witnesses tell us he released some sort of canister. They heard a hissing sound and some gas emerged and the gunman opened fire," Oates said at a news conference.

It was the worst mass shooting in Colorado since the Columbine High School massacre on April 20, 1999. Students Eric Harris, 18, and Dylan Klebold, 17, opened fire at the school in the Denver suburb of Littleton, about 15 miles west of Aurora, killing 12 classmates and a teacher and wounding 26 others before killing themselves in the school's library.

Aurora police spokesman Frank Fania on ABC's "Good Morning America" said 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.

KUSA-TV posted an interview with two witnesses who told a similar story about a man dressed in all black and a bullet proof vest who barged in through the emergency exit. After throwing some sort of device that exploded, that's when he opened fire. But people did not react right away because, they said, they thought it was an act that was part of the movie:

KUSA has more from the witnesses:

"He looked so calm when he did it," the eyewitness said. "It was like scary. He waited for both the bombs to explode before he did anything. Then, after both of them exploded, he began to shoot."

The witnesses said he - at first - fired into the air and then started shooting towards the people.

"He had no specific target. He just started letting loose," the eyewitness said.

Both witnesses said one of the scariest parts was the shooter didn't say a word.

"Honestly, I thought I was gonna get shot," the eyewitness said. "I thought there was no way I was going to get out of there without getting shot."

The "Today" show interviewed another witness who tells the incredible story of the gunmen pointing his weapon at her but not firing after she dove for the aisle:

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Police, ambulances and emergency crews swarmed on the scene after frantic calls started flooding the 911 switchboard, officials said.

Officers found the gunman near a car behind the theater.

"A gas mask, rifle, handgun at least one additional weapon (were) found inside" he said.

The suspect was taken into custody, but no name was released. Oates said there's no evidence of any other attackers. There was also no immediate word of any motive.

The suspect spoke of "possible explosives in his residence. We are dealing with that potential threat," Oates said, without providing details on where that was.

Reuters reports other outlets have said the shooter may be in his early 20s and fired anywhere from 10-20 shots. The local Fox affiliate, KDVR-TV, reports he is a "24-year-old white male."

He said police also checked for explosives in the parking lot and theater, and secured those areas.

Witness Hayden Miller told KUSA that he was inside Theater 16 and heard several shots.

"Like little explosions going on and shortly after that we heard people screaming," he told the station.

Hayden said at first he thought it was part of a louder movie next door. But then he saw "people hunched over leaving theater."

Another witness describes seeing an officer carrying out a motionless little girl in the aftermath:

CNN played YouTube video of some of the chaos around the theater seemingly after the theater. However, that video shows at least one bloodied victim walking around dazed as an officer escorts him out:

You can see that video in its entirety below (warning: graphic content):

The police chief said 10 victims died at the theater and four at area hospitals.

Two people in critical condition were rushed to nearby Swedish Medical Center, spokeswoman Nicole Williams said.

She said emergency crews told her staff to prepare for several more patients from the shooting scene.

"We're on standby to receive," she said.

Aurora is on Denver's east side and is Colorado's third-largest city with 327,000 residents. It is home to a large Defense Department satellite intelligence operation at Buckley Air Force Base, as well as The Children's Hospital, the University of Colorado Hospital and a future Veterans Affairs hospital.

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*Police originally reported 14 were killed. That number has been revised down to 12.

UPDATE II: President Obama issued a statement saying he and Michelle were "shocked and saddened." Mitt Romney also commented, saying he and his wife Ann are "deeply saddened" by the "senseless violence." You can read those statements here.

UPDATE III: You can listen to the frantic 911 calls and police communications here.