Here's a guide to some key questions in the wake of the mass shooting at a Colorado movie theater during a showing of "The Dark Knight Rises."
Q: WHAT HAPPENED?
A: On Friday, shortly after midnight Thursday, a gunman wearing a gas mask and black SWAT gear set off two gas canisters and then opened fire inside a crowded theater in the Denver suburb of Aurora, Colo., killing 12 people and wounding nearly 60 others, authorities said. The suspect was arrested near a car behind the theater and identified as 24-year-old James Holmes. Authorities have not released a motive.
Q: WHO IS THE SUSPECT?
A: Holmes was studying neuroscience in a Ph.D. program at the University of Colorado-Denver. He enrolled in June 2011 but left a year later, though it wasn't immediately clear why.
He played soccer at Westview High School in the San Diego area and graduated with honors from the University of California, Riverside, in spring 2010 with a bachelor's degree in neuroscience.
Those who knew Holmes described him as a shy, intelligent man who grew up in San Diego with parents who were active in their well-to-do suburban neighborhood.
Q: WHAT IS GOING ON AT HOLMES' APARTMENT?
A: Police disarmed trip wires and explosive devices that authorities said were "set up to kill" people inside Holmes' third-floor apartment. They detonated one small explosive and disarmed another, but several other explosive devices remained, Aurora police Sgt. Cassidee Carlson said Saturday.
Authorities are hoping to find clues to his motive without destroying key evidence in a blast.
Police have evacuated surrounding buildings. The apartment is about four miles from the theater.
Q: ARE MOVIE THEATERS STILL SHOWING THE FILM?
A: Yes, though with increased security. AMC Theaters, the nation's second-largest chain, barred customers from wearing masks or costumes.
Also, in a rare show of solidarity, Hollywood studios delayed their weekend box-office reporting because of the shootings. Sony, Fox, Disney, Universal and Lionsgate said Saturday that they were joining "Dark Knight Rises" distributor Warner Bros. in withholding their box-office numbers for the weekend.
The film was expected to be among the most lucrative movie openings, but that now appears unlikely. However, Hollywood trade publications Variety and Hollywood Reporter reported estimates of roughly $75 million to $77 million for the film on Friday, based on box-office insiders. That would put it on track for somewhere around $165 million for the weekend. Such a total would be the second-highest weekend opening ever, after "The Avengers" brought in $207.4 million.
Q: WHO WAS HURT IN THE THEATER?
A: Many victims treated at hospitals were under 40, including a 4-month-old baby. The oldest reported patient was 45. The youngest victim who died was a 6-year-old girl.
Victims were treated for chemical exposure, apparently related to the canisters thrown by the gunman, and gunshot and shrapnel wounds.
The Defense Department said a sailor and an Air Force Reservist also died in the shooting.
Also among the slain were a sports blogger who recently wrote about surviving a shooting in Canada and a man celebrating his 27th birthday and first wedding anniversary.
Q: WAS THERE ANY LINK BETWEEN THE SHOOTING AND THE MOVIE?
A: It's unclear. New York City's police commissioner said he was told the gunman had painted his hair red and called himself the Joker — Batman's nemesis — but Aurora police would not confirm that.
In "The Dark Knight Rises," a masked villain leads a murderous crew into a packed football stadium and wages an attack involving guns and explosives. But violent attacks on the public by villains are key components of most superhero movies.
There are general parallels to the shooting, "The Dark Knight" and the comic book character. Bruce Wayne's drive to become Batman arose from witnessing the deaths of his parents at the hands of a criminal who shot and killed them after they left a movie. The Batman video game called "Arkham City" takes place in an abandoned movie theater.
Q: HOW MANY GUNS DID THE SUSPECT HAVE?
A: Four. Officers found an AR-15 assault rifle — the civilian form of the M-16, a Remington 12-gauge shotgun and a .40-caliber Glock handgun in the theater, and another identical handgun in the car. The gunman also set off two devices that released smoke or an irritant, Aurora Police Chief Dan Oates said.
Q: WHEN WAS THE LAST MASS SHOOTING IN THE U.S.?
A: The massacre in Aurora was one of the deadliest in the U.S., and 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 wounded more than two dozen others.
In Colorado, it was the deadliest shooting since April 20, 1999, when two students opened fire at Columbine High School in the Denver suburb of Littleton, killing 12 classmates and a teacher and wounding 26 others before killing themselves.