Aurora, Colorado, Century Movie Theater 'Dark Knight Rises' shooting: 12 confirmed dead (LIVE VIDEO)

AURORA, Colo. -- A gunman wearing a gas mask set off an explosive device and then fired into a crowded movie theater near the Aurora Mall, killing 12 people and injuring at least 38 others during a midnight opening of the Batman movie "The Dark Knight Rises."

Police arrested a man wearing a gas mask next to a white car in the parking lot behind the theater. 7NEWS has confirmed that the suspect is a 24-year-old white man, James Holmes.

Moviegoers said they didn't know what was happening and some thought the attack was part of the movie, since it occurred during a battle scene. Then they saw a silhouette of a person in the smoke at the front of the theater near the screen, pointing a gun at the crowd.

Many of those injured or killed are teens or kids. They have not been identified.

Some victims are being treated for chemical exposure apparently related to canisters thrown by the gunman. More than 250 police officers from across the metro area -- from Brighton to Jefferson County -- were called out to respond.

Ten people died in the theater, two more died at nearby hospitals. The Police Department previously released a preliminary number of 14 dead, but only 12 can be confirmed at this time. Approximately 50 total persons were shot, including the deceased, police said.

Witnesses told 7NEWS that the bullets were fired in theater 9, but bullets also pierced the nearby theater and injured moviegoers in that theater. The entire parking lot around the Century 16 Movie Theaters was blocked off. Aurora Police Chief Dan Oates said there was no evidence of additional shooters.

FBI spokesman Jason Pack said there's no indication in the investigation so far of any connection to terror groups. There was no immediate word of any motive. Investigators were outside the suspect's apartment in North Aurora and had evacuated other residents of the area, police said.

Treating The Injured

A spokeswoman for Swedish Hospital said the hospital went on alert at 1:15 a.m. and began calling in extra staff. Swedish Hospital received three patients, all of them with gunshot wounds.

Two patients were in surgery as of 4 a.m. Those victims are a 20-year-old woman and a 29-year-old man. Both were in critical condition and in surgery at 4 a.m., according to a hospital spokeswoman. The third victim was treated and released.

University Hospital said it has 20 victims with minor to severe injuries. Nine of those victims are critical.

The victims taken to University Hospital are mostly adults, but some are teenagers. The youngest victim was a 3-month-old child.Children's Hospital told 7NEWS it was treating six victims from the theaters.

They range in age from six to 31.Denver Health said it took six patients from the Aurora shooting. One is in critical condition and the other five are in fair condition.

More victims were taken to Aurora South Hospital.President Barack Obama said he was "shocked and saddened" when he learned about the shooting. He is urging the nation to "come together as one American family."

Suspect Captured; Alluded To Other Weapons, Bombs

Holmes was arrested in the parking lot of theater, police said. Witnesses said he was dressed in black and was wearing a gas mask and bulletproof vest.

He was found with two weapons in his possession, a rifle and a handgun, police said. Investigators said they recovered a third weapon, but they did not say where that weapon was found or what it was.

Holmes alluded to bombs at his house, police said. Investigators are at that apartment at Paris Street and 17th Avenue in North Aurora and have evacuated the building and the nearby area.

7NEWS has learned that Holmes lived in apartment 10. A bulletin was issued to other police agencies throughout the metro area warning them of the possibility of similar incidences in theaters in their cities.

This is 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.

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WATCH LIVE VIDEO FORM THE SCENE HERE : http://bit.ly/NFzDHt