A day after a gunman opened fire at a packed midnight showing of the new "Batman" film in a Denver suburb, killing 12 people and wounding 59 more, police on Saturday prepared to neutralize explosives in the suspect's booby-trapped apartment.
Dozens of law enforcement officials arrived at the apartment of suspect James Holmes at dawn, but it was not immediately clear if they planned to detonate the suspected explosives using a robot. Police have evacuated five nearby buildings and created a perimeter of several blocks.
Meanwhile, a memorial of flowers and candles has been set up at the Aurora shopping mall where the shooting rampage at a showing of "The Dark Knight Rises" turned a movie screening into a chaotic scene of dead or bleeding victims. A handwritten sign read: "7/20 gone not forgotten."
On Friday, the police chief in Aurora said the apartment was "booby-trapped," and it could be days before the explosives and flammable material could be removed. Police found jars of chemicals in the apartment with wires nearby, a law enforcement official told The Associated Press.
Authorities identified the suspect as 24-year-old James Eagen Holmes and said he had been armed with an AR-15 assault rifle, a shotgun and two Glock pistols.
Investigators ruled out a link to terrorism at this time and said they believed he acted alone. There was no word on a motive.
Holmes has asked for a lawyer and is refusing to talk to investigators, a law enforcement official briefed on the investigation told the AP. A court appearance is scheduled for Monday.
A federal official told the news agency that Holmes bought a ticket to the midnight showing of the latest Batman movie and went into the theater as part of the crowd.
The law enforcement official, who spoke on the condition of anonymity, said Holmes is believed to have propped open an exit door as the movie was playing, donned protective ballistic gear and opened fire.
Holmes was studying neuroscience in a Ph.D. program at the University of Colorado-Denver, university spokeswoman Jacque Montgomery said. Holmes enrolled a year ago and was in the process of withdrawing, Montgomery said. Earlier, Montgomery was quoted as saying Holmes had recently dropped out of medical school.
Police released a written statement from Holmes' family, who live in the San Diego area: "Our hearts go out to those who were involved in this tragedy and to the families and friends of those involved."
It was the worst mass shooting in the U.S. since the Nov. 5, 2009, attack at Fort Hood, Texas, when an Army psychiatrist killed 13 soldiers and civilians and more than two dozen others wounded.
The production company of one of the most widely anticipated movies of the summer, Warner Bros., and the owner of the Century 16 Movie Theaters in Aurora said in separate statements that they were "deeply saddened."
"We extend our sincere sympathies to the families and loved ones of the victims at this tragic time," the Time Warner company said in a statement.
The company immediately canceled plans for a red carpet premiere in Paris for Friday night and for media interviews there with director Christopher Nolan and cast members Christian Bale, Anne Hathaway and Morgan Freeman. Workers pulled down the red carpet display in front of the theater on the Champs-Elysees and carried away a large mask from the theater facade. Regular showings continued.
In its statement, Cinemark Holdings praised emergency responders for "quick and professional reaction." "Our thoughts and prayers are with the victims, their families and loved ones, our employees, and the Aurora community," it said.
Asked at a news conference about security at the theater, Cinemark CEO Tim Warner said the gunman was "well organized." "He had an assault weapon that would probably have overpowered any security that we would have had. Obviously, a very deranged gunman that had access to very powerful weapons."
In New York, Police Commissioner Ray Kelly said the NYPD will provide extra security coverage at theaters featuring the movie "as a precaution against copycats and to raise the comfort levels among movie patrons."
President Barack Obama said he was "shocked and saddened" by the rampage. He cut short a planned two-day campaign swing through Florida and to return to the White House.
"As we do when confronted by moments of darkness and challenge, we must now come together as one American family," Obama said. "All of us must have the people of Aurora in our thoughts and prayers as they confront the loss of family, friends, and neighbors."
GOP presidential candidate Mitt Romney said he and his wife, Ann, were "deeply saddened by the news of the senseless violence." He said they were 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."
New York City Mayor Michael Bloomberg called on Obama and Romney to respond to the mass shooting by detailing their plans to improve gun control.
"Soothing words are nice," Bloomberg said in his weekly WOR Radio appearance, but added that it's time to hear the candidates "stand up and tell us what they're going to do about it."
Police said 12 people were killed atthe multiplex in the Aurora Town Center, lowering an earlier death toll by two. The youngest of those wounded — a 4-month-old baby — survived, authorities said.
"This is one of the most horrific nights I've ever had to work," said Comilla Sasson, an emergency doctor at the University of Colorado Hospital in Aurora, where the baby and 21 other patients were treated. Other victims were treated elsewhere.
Wearing a gas mask, the attacker barged into the crowded theater, hurled a gas canister and then opened fire.
When the gas began to spread, some moviegoers said, they thought it was a stunt that was part of the movie. They then saw a silhouette of a person in the smoke near the screen, first pointing a gun at the crowd and shooting.
The film has several scenes of public mayhem. In one scene, the main villain Bane leads an attack on the stock exchange and, in another, leads a shooting and bombing rampage on a packed football stadium.
It was the final installment of the "Dark Knight" trilogy directed by Nolan and starring Bale as Batman. For the first one, "The Dark Knight," Heath Ledger was awarded a posthumous Oscar for his searing portrayal of The Joker.
Jennifer Seeger, 25, said she was in the second row, about 4 feet from the gunman. She said he pointed a gun at her face and felt like "just a deer in headlights," but she ducked.
"There were bullet (casings) just falling on my head. They were burning my forehead," she said, adding that the gunman, dressed like a SWAT team member, fired steadily except when he stopped to reload.
"Every few seconds it was just: boom, boom, boom."
"Every few seconds it was just: boom, boom, boom," she said. "He would reload and shoot and anyone who would try to leave would just get killed."
She said she began crawling toward an exit when she saw a girl about 14 years old "lying lifeless on the stairs."
"It was mass chaos," Seeger told NBC's "TODAY." The gunman shot the ceiling and then "he threw in the gas can, and then I knew it was real."
"Everyone's going for the door and then everyone starts saying, 'No, he's going to shoot people going for the door, and he did," she told NBC. "They're trying to escape, and he shot those people as well."
Police, ambulances and emergency crews swarmed the scene after frantic calls started flooding the 911 switchboard, officials said.
Officers came running in and telling people to leave the theater, Salina Jordan told The Denver Post. She said some police were carrying and dragging bodies.
"When we got out of the theater it was just chaos. There was this one guy who was on all fours crawling. There was this girl spitting up blood," Donovan Tate told KCNC television. "There were bullet holes in some people's backs, some people's arms. There was this one guy who was stripped down to just his boxers. It looked like he was shot in the back or something. It was crazy."
Officers later found the gunman near a car behind the theater and he was taken into custody.
The weapons were bought from two local stores of two national chains, Gander Mountain Guns and Bass Pro Shop, beginning in May, law enforcement officials told NBC News.
The suspect spoke of "possible explosives in his residence. We are dealing with that potential threat," Aurora Police Chief Dan Oates said.
Police at the suspect's North Aurora apartment evacuated other residents of the building. Oates said the apartment was booby-trapped. "We are trying to determine how to disarm the flammable or explosive material," he said. "It could be a very long wait."
Oates said police also checked for explosives at the massacre scene and secured those areas.
Another survivor, Benjamin Fernandez, 30, told the Post he heard a series of explosions. He said that people ran from the theater and there were gunshots as police shouted "get down!"
Fernandez said he saw people falling, including one young girl.
Hayden Miller told KUSA-TV he heard several shots. "Like little explosions going on and shortly after that we heard people screaming," he said.
Miller said at first he thought it was part of a louder movie next door. But then he saw "people hunched over leaving theater."
Salina Jordan, 19, told the Post she was in Theater 8 and saw people hit in her theater. She said one girl was struck in cheek, others in stomach including a girl who looked to be around 9 years old, according to the Post.
Most of the wounded and killed were at Theater 9 of the multiplex, the Post said.
Obama said the administration will do everything possible to support the community. The White House said Obama was informed of the shooting by Homeland Security Adviser John Brennan at 5:26 a.m. EDT.
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.
The town is also 20 miles northeast of Littleton, where two teen gunmen massacred 13 people in a suicide attack at Columbine High School in 1999.
The massacre stunned Aurora and much of the nation, evoking memories of the 1999 massacre at Columbine High School in Littleton, 17 miles (27 km) from Aurora, where two students opened fire and killed 12 students and a teacher.
It also resonated in the U.S. presidential race as both President Obama and Romney toned down their campaigns, pulled their ads from Colorado and dedicated their scheduled events to the victims on Friday.
Chris Henderson, Aurora's deputy fire chief, said Holmes' living room was found crisscrossed with trip wires connected to what appeared to be plastic bottles containing an unknown liquid.
A law enforcement source told Reuters the suspect had also set a timer to turn on loud music in his apartment—playing the same song over and over again—apparently in an attempt to prompt a complaint and lure police into a trap.
"If he was shot and killed, it is without a doubt that these ... booby traps were there to murder and inflict casualties upon first responders," the source said.
With Holmes in jail and awaiting an initial court appearance on Monday morning, police have declined to reveal what he has told investigators and would not discuss possible motives for the shooting rampage.
Meanwhile little has surfaced from the suspect's past to suggest he was capable of such violence.
Raised in a middle-class San Diego neighborhood, he earned a degree in neuroscience from the University of California at Riverside before seeking his graduate degree from the University of Colorado.
Holmes was described by acquaintances as bright but was in the process of dropping out of his graduate program at the time of the shooting, according to the university.
Billy Kromka, a pre-med student who worked alongside Holmes in a neuroscience research lab last year, said he was astonished when he saw a picture of the accused gunman.
"He basically was socially awkward but not to the degree that would warrant suspicion of mass murder or any atrocity of this magnitude," Kromka told Reuters in an interview. "I did not see any behavior he exhibited that indicated he would be capable of an atrocity of a magnitude like this."
Kromka, 19, said he knew Holmes to sometimes play video games in the lab when he was supposed to be working, and said he seemed to be influenced by movies and the media.