About 50 people have been hurt and at least 12 are dead after a gunman opened fire early Friday at a suburban Denver movie theater on the opening night of the latest Batman movie "The Dark Knight Rises."

The gunman, who is in custody and has been identified as 24-year-old James Holmes, stood at the front of the theater and fired into the crowd about 12:30 a.m. MDT at a multiplex theater in a mall in Aurora, which is located on the southeast outskirts of Denver, about 10 miles from downtown.

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

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

Officers found the gunman near a car behind the theater. Officials say that up until now Holmes had a clean record. 

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

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.

He said police also checked for explosives in the parking lot and at the Century 16 theater and secured those areas.

Witness Hayden Miller told KUSA-TV 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."

The police chief said 10 victims died at the theater. The other two are believed to have died 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.

The youngest victim reported was a 6-year-old being treated at Children's Hospital Colorado, where a total of six victims were taken. Their condition wasn't known.

President Barack Obama said upon hearing the news he was "shocked" and "saddened." 

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