Batman Shooting (VIDEOS) James Holmes Shooter. A gunman burst into an Aurora, Colo., movie theater showing the new Batman movie and opened fire Friday, killing at least 12 people and wounding about 50.

Police said the heavily armed man wearing body armor was taken into custody in the theater's parking lot without incident, KUSA-TV, Denver, reported.

The suspect was identified as James Holmes (PHOTOS), 24, of Aurora by several media outlets.

"He did not resist. He did not put up a fight," Aurora Police spokesman Frank Fania told CNN.

Police evacuated the apartment building where the suspect lived and were searching the building for possible explosives after Holmes "made a statement about explosives" in his unit, Aurora Police Chief Dan Oates said.

Aurora, part of the Denver metropolitan area, is about 17 miles from Littleton, Colo., scene of the 1999 Columbine High School massacre in which two students shot and killed 12 students and one teacher, and wounded 21 other people before committing suicide.

Police initially said 14 were killed in Friday's massacre but later revised the death toll to 12.

Witnesses said the suspect entered the theater during the midnight screening of "The Dark Knight Rises," threw some type of explosive and started shooting into the crowd at Century 16 Movie Theaters at the Aurora Town Center.

The man had a rifle, a handgun and a gas mask when police arrested him, The Denver Post said.

Police said there were no indications others were involved in the shooting.

Oates said witnesses said the gunman was dressed in black and wore a gas mask.

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

Witnesses told KUSA the suspect tossed two gas canisters into the theater after breaking down the emergency exit door. Many movie-goers initially thought the sound of gunfire was coming from the movie or from a movie shown in an adjacent theater, or was part of a publicity stunt, KUSA said.

"He looked so calm when he did it," a witness 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."

Witnesses said the suspect first fired into the air, then starting shooting at people.

"He had no specific target. He just started letting loose," another witness told KUSA.

Witness Salina Jordan, 19, told the Post she was in an adjacent theater and saw people getting hit. She said it sounded like firecrackers until someone ran into the theater yelling, "They're shooting out here!"

The Post said victims were transported to at least six hospitals with injuries of varying severity.

CNN said cellphone video showed scores of people screaming and fleeing the theater complex, some with bloodied clothes.

One witness said a police officer was seen carrying a young girl with gunshot wounds to her back from the theater.

"She wasn't moving," the witness said.

Hundreds of police officers arrived at the theater and the FBI has joined the investigation.

"We were calling for help from every police and fire agency," Fania said.

President Obama said his administration "will do everything that we can to support the people of Aurora in this extraordinarily difficult time."

"We are committed to bringing whoever was responsible to justice, ensuring the safety of our people, and caring for those who have been wounded," Obama said in a statement. "As we do when confronted by moments of darkness and challenge, we must now come together as one American family. All of us must have the people of Aurora in our thoughts and prayers as they confront the loss of family, friends, and neighbors, and we must stand together with them in the challenging hours and days to come."

Presumptive Republican presidential nominee Mitt Romney also expressed sorrow regarding the shooting.

"Ann and I are deeply saddened by the news of the senseless violence that took the lives of 15 people in Colorado and injured dozens more," he said in a statement. "We are praying for the families and loved ones of the victims during this time of deep shock and immense grief. We expect that the person responsible for this terrible crime will be quickly brought to justice."