The semiautomatic assault rifle used by the gunman in a mass shooting at a midnight showing of the latest Batman movie jammed during the attack, a federal law enforcement official told The Associated Press, forcing the shooter to switch to another gun with less firepower.
The official, who spoke on condition of anonymity to discuss the investigation, said the disabled weapon had a high-capacity ammunition magazine. Police have said a 100-round drum magazine was recovered at the scene and that such a device could fire 50 to 60 rounds a minute.
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That account of what happened inside the Century 16 theater emerged along with other details of the suspect, James Holmes, 24, who police said was described as a budding scientist, brimming with potential, who pursued a graduate program even as he planned the attack with "calculation and deliberation."
An official also said Sunday that investigators found a Batman mask inside the Holmes' apartment.
Holmes is being held at the Arapahoe County jail and is to be arraigned Monday in the County Court, outside Denver. Holmes isn't talking to police and appears to have acted alone, authorities said.
Authorities said 25 of the 58 injured in the movie theater attack remained in hospitals. Nine of the 25 are described as being in critical condition. Twelve were killed in the shooting that occurred about 12:30 a.m. Friday, a half-hour into a showing of "The Dark Knight Rises."
Holmes had applied to join a Colorado gun range last month but never became a member because of his behavior and a "bizarre" message on his voice mail greeting, the range's owner said Sunday.
Holmes emailed an application to join the Lead Valley Range in Byers, Colo., on June 25, in which he said he was not a user of illegal drugs or a felon, said owner Glenn Rotkovich. But when Rotkovich called to invite him to a mandatory orientation the following week, he said he heard Holmes' voice mail greeting, which he said was "bizarre -- guttural, freakish at best."
Rotkovich said he told his staff not to accept Holmes into the club, Rotkovich said. His comments were first reported by Fox News.
Throughout the day Sunday, police in Aurora continued to collect evidence from Holmes' apartment. Police and Federal Bureau of Investigation agents used a robot Saturday to disarm a tripwire and clear bombs from Holmes' apartment, which remained cordoned off.
They announced they had cleared all hazardous items from the unit Sunday and allowed residents in neighboring buildings to return home.
Investigators are examining how he obtained materials used in the shootings and to booby-trap his apartment, said police Chief Dan Oates on the CBS program "Face the Nation."
"All evidence we have, every single indicator, is that it was all Mr. Holmes' activity and that he wasn't particularly aided by anyone else," Oates said.
Police said Holmes, carrying the AR-15 and the other weapons, walked into the theater about 20 minutes into the movie. He wore a gas mask and a ballistics helmet and vest, as well as groin, throat and leg protectors. He allegedly released two smoke- or gas-emitting devices, and then opened fire, shooting at anyone who tried to escape.
Holmes bought the weapons legally in the past 60 days from local gun shops, Oates has said. Holmes also had also purchased more than 6,000 rounds of ammunition -- 3,000 for the assault rifle, 3,000 for the two handguns and 300 rounds for the shotgun.
"All weapons he possessed, he possessed legally. All clips he possessed, he possessed legally. All ammunition he possessed, he possessed legally," Oates said Friday.
Rep. Carolyn McCarthy Sunday disputed the contention that the shooting would have been averted if more people in the theater had guns.
"It's smoky, it's dark, everyone starts shooting," McCarthy (D-Mineola) said on NBC's "Meet the Press." "Everything would have been a lot worse."
McCarthy, who lost her husband in a 1993 mass shooting on the Long Island Rail Road, ran for Congress as a proponent of more stringent gun control. She appeared on the news show alongside Michael Chertoff, former secretary of Homeland Security during the Bush administration, and William Bratton, the former chief of police for the Los Angeles Police Department and NYPD commissioner.
Bratton agreed with McCarthy, saying, "In this circumstance, [more guns] wouldn't have made a difference."
McCarthy knocks NRA
McCarthy spoke critically about the National Rifle Association's long-held opposition to stronger gun-control policy and said the public should call for more, and not more relaxed, gun control legislation.
"As horrible as this tragedy was, and is, you have to remember how many people are killed everyday by illegal guns," McCarthy said.
Chertoff, noting that Holmes also used explosives and pointing to the ability of individuals to make such explosives in their homes, said the focus should be "people, not the tools," and how law enforcement officials can better detect mental health issues. "We need to understand more about the signs that shows someone becoming deranged or a terrorist," Chertoff said.
"This requires -- particularly in a presidential year -- the candidates for president of the United States to stand up and once and for all say, yes, they feel terrible. Yes, it's a tragedy. Yes, we have great sympathy for the families, but it's time for this country to do something," Bloomberg said on CBS. "And that's the job of the president of the United States."
Holmes had recently withdrawn from a competitive graduate program in neuroscience at the University of Colorado in Denver.