AURORA, Colo. — A former neuroscience honors student dressed in full body armor and carrying three weapons, including an assault rifle, opened fire in a crowded theater at a midnight showing of the new Batman movie early Friday, killing at least 12 people and wounding 59 others, police and federal officials said.
The suspect, James Holmes, 24, was arrested within minutes in the parking lot of the Aurora multiplex theater that was showing the much-anticipated sequel, “The Dark Knight Rises.’’ The attack was so bizarre that many audience members first thought it was a stunt associated with the movie.
Holmes told investigators after his arrest that he had booby-trapped his apartment in Aurora, a Denver suburb, with explosive devices. That led police to evacuate five buildings in the neighborhood as they disabled what they called ‘‘incendiary and chemical devices’’ that appeared to be rigged to trip wires.
Police believe Holmes acted alone, and said he had no known links to terrorist organizations. Investigators have uncovered no solid indications of a motive.
The injuries of the victims included gunshot wounds and shrapnel injuries, hospital officials said. At least 12 people were in critical condition, and there were fears that the death toll might rise.
While some witnesses said the gunman entered through a side-door emergency exit at the front of the theater, a federal law enforcement official, speaking on condition of anonymity, said Holmes bought a ticket and went into the theater as part of the crowd, the Associated Press reported.
The official said Holmes then apparently propped open an exit door in the theater as the movie was playing, donned the protective ballistic gear, and began his attack.
Witnesses said Holmes, who wore a gas mask, set off two smoke devices before firing randomly at audience members, who had just settled into their seats. Within minutes, he was arrested in a parking lot behind the theater near his car, the police said.
Holmes had apparently planned the attack for some time: In addition to the gas mask, he wore body armor and a ballistic helmet and was dressed completely in black. His gear included a throat protector, a groin protector, a bulletproof vest and leggings, and tactical gloves.
He entered the theater with an AR-15 assault rifle, a Remington 12-gauge shotgun, and a .40-caliber Glock handgun. A fourth gun, another Glock pistol, was found in his car.
Federal law enforcement officials said information they had obtained about the purchase of the AR-15 rifle indicates that it was bought locally and apparently legally, as were the other guns.
The suspect had a clip with more than 20 rounds, a federal official said, that would have been illegal under the assault rifle ban, which expired in 2004. The Bureau of Alcohol, Tobacco, Firearms, and Explosives handed over information on where and when the guns were purchased to the police in Aurora.
Investigators found no evidence of any past aberrant behavior by Holmes. ‘‘He’s not on anybody’s radar screen — nothing,’’ a law enforcement official said. Holmes’s only criminal history is a traffic summons, the authorities said.
President Obama said he was saddened by the ‘‘horrific and tragic shooting,’’ pledging that his administration was ‘‘committed to bringing whoever was responsible to justice, ensuring the safety of our people, and caring for those who have been wounded.’’
It was the worst mass shooting in the United States since the Nov. 5, 2009, attack at Fort Hood, Texas. In Colorado, it was the deadliest since the Columbine High School massacre April 20, 1999, when two students opened fire in the Denver suburb of Littleton, killing 12 classmates and a teacher.
‘‘This is the act, apparently, of a very deranged mind,’’ said Governor John Hickenlooper of Colorado.
New York City Police Commissioner Raymond W. Kelly, who dispatched officers to patrol screenings of the film in New York, said he had been told the shooting suspect had hair painted red and said he was the Joker. That detail could not be initially confirmed.
Holmes earned a bachelor’s degree with honors in neuroscience in 2010 from the University of California, Riverside, and was a graduate student in neurosciences at the Anshutz Medical Campus of the University of Colorado, although the university said in a statement that he was in the process of withdrawing. He was currently collecting unemployment, a federal law enforcement official said.
A spokeswoman for the university, Jackie Brinkman, said that Holmes was dropping out of school because of academic problems. Brinkman said the university was unaware of any incidents with the campus police or disciplinary problems involving Holmes while he was enrolled.
Aurora Police Chief Dan Oates said he did not know how many shots the gunman had fired, saying only that it was ‘‘many, many rounds,’’ one of which passed through a wall and wounded a moviegoer in an adjoining theater.
The authorities have not released the names of victims, but a family member identified one of them as Jessica Ghawi, who was also known as Jessica Redfield.
Ghawi, 24, was a sports blogger who recently wrote of surviving a Toronto shooting. Ghawi blogged at length about the Eaton Centre mall shooting that killed two people and sent several others to the hospital.
The injuries of the Colorado victims included gunshot wounds and shrapnel injuries, hospital officials said. At least 12 people were in critical condition.
The shooting erupted at the Century 16 Movie Theater during the first showings of ‘‘The Dark Knight Rises.’’
Throngs had gathered, some dressed as characters from the Batman sequel. The four screenings of the film were sold out, although it is not quite clear how many people were inside at the time.
Obama, in Florida as part of a campaign swing, was notified of the shooting by his top counterterrorism adviser, John O. Brennan, at 5:26 a.m., the White House said.
“We do not believe at this point there was an apparent nexus to terrorism,’’ Jay Carney, the White House press secretary, told reporters on Air Force One.
Obama returned to Washington on Friday afternoon, cutting short his Florida trip, his campaign said. In remarks at a previously scheduled stop in Fort Myers, Fla., Obama talked in highly personal ways about the tragedy.
‘‘My daughters go to the movies,’’ he said. ‘‘What if Malia and Sasha had been in the theater as so many of our kids do every day? Michelle and I will be fortunate enough to hug our girls a little tighter tonight.’’
Both Obama and Mitt Romney, the presumed Republican presidential nominee, said they planned to pull television campaign ad s in Colorado.
A spokesman for Warner Bros. said the studio pulled its trailer for an upcoming film, ‘‘Gangster Squad,’’ which is set for release in September. In the trailer, which was shown at some screenings of ‘‘The Dark Knight Rises,’’ but not in the Aurora theater, men are seen shooting into the crowd in a movie theater.
Mayor Michael R. Bloomberg of New York, who has waged a national campaign for stricter gun laws, called on Obama and Romney to more concretely address the issue of gun violence in their campaigns.
‘‘You know, soothing words are nice,’’ Bloomberg said during his weekly radio program, ‘‘but maybe it’s time that the two people who want to be president of the United States stand up and tell us what they are going to do about it, because this is obviously a problem across the country.’’