AURORA, Colo. July 20, 2012 -- Suspected Colorado movie theater gunman James Holmes purchased four guns at local shops and more than 6,000 rounds of ammunition on the Internet in the past 60 days, Aurora Police Chief Dan Oates told a news conference this evening.

"All the ammunition he possessed, he possessed legally, all the weapons he possessed, he possessed legally, all the clips he possessed, he possessed legally," an emotional Oates said.

The chief declined to say whether the weapons were automatic or semi-automatic, but "he could have gotten off 50 to 60 rounds, even if it was semi-automatic, within one minute," Oates said.

Authorities have yet to identify the 10 victims who died at the theater. Two other people died at the hospital, including 24-year-old aspiring sportscaster Jessica Ghawi, for a total of 12 dead. Thirty people remained hospitalized, 11 of them in critical condition, Oates said.

Fifty eight people were injured, most of them by gunfire but a "handful" during the ensuing chaos, Oates said. One person was hit in an adjacent theater.

As for the dead, Oates said he hoped soon to get a "confirmed list of the 10 deceased and we will begin the agonizing process of meeting with those families and confirming what has happened to their loved ones."

Gov. John Hickenlooper opened the news conference this evening, saying, "We are seeing this community rise up and do the things that communities do.

At times lost for words, he repeatedly praised the efforts of the first responders.

The shooting occurred during a sold-out midnight premiere of the new Batman movie, "The Dark Knight Rises," when Holmes, 24, allegedly unloaded four weapons' full of ammunition into the unsuspecting crowd.

The number of casualties makes the incident the largest mass shooting in U.S. history.

An honors student and Ph.D. candidate at a nearby college with a clean arrest record, Holmes allegedly entered the movie auditorium wearing a ballistics helmet, bulletproof vest, bulletproof leggings, gas mask and gloves. He detonated multiple smoke bombs, and then began firing at viewers in the sold-out auditorium, police said today.

Holmes, who is being held in jail and will make his first court appearance Monday, is originally from Riverside, Calif., where he attended the University of California branch, Oates told the news conference this evening. "Neighbors report that he lived alone and kept to himself," Oates added.

Oates also offered a warning about the veracity of online information. "In the era of blogs," he said, "and everything else, we just caution you that everything you read may not be true."

He added that two local high schools will be offering grief counseling Saturday.

Bullets from the shooting spree tore through the theater and into adjoining theaters, where at least one other person was struck and injured. Ten members of "The Dark Knight Rises" audience were killed in the theater, while two others died later at area hospitals. Numerous patrons were in critical condition at six local hospitals, the Aurora police said this afternoon.

Authorities began removing the bodies this afternoon, according to ABC News Denver affiliate KMGH-TV. Several people have been reported missing as the coroner identifies the dead.

Holmes was apprehended within minutes of the 12:39 a.m. shooting at his car behind the theater, where police found him in full riot gear and carrying three weapons, including an AR-15 assault rifle, which can hold upwards of 100 rounds, a Remington 12-gauge shotgun, and a .40 Glock handgun. A fourth handgun was found in the vehicle.

Agents from the federal bureau of Alcohol, Tobacco, and Firearms are tracing the weapons.

According to police sources, Holmes told the officers arresting him that he was "The Joker," referring to the villain in the second installment of the Batman movie trilogy, "The Dark Knight." He also warned police that he had booby-trapped his apartment, leading officers to evacuate the Aurora apartment building.

Chief Oates earlier today said that police, bomb squads and the ATF have found a large number of explosive devices and trip wires at Holmes' apartment and have not yet decided how to proceed without setting off explosions.

"The pictures we have from inside the apartment are pretty disturbing considering how elaborate the apartment is booby trapped," police said outside of the apartment complex today. The "flammable and explosive" materials could have blown up Holmes' apartment building and the ones near it, police said.

The apartment complex is home exclusively to University of Colorado Medical Center students, patients and staff members, residents told ABC News.

Oates this evening said police will allow residents to retrieve personal belongings but leave the booby-trapped apartment alone for now, and inspect them Saturday with the help of federal law enforcement. Residents are staying at a local high school in the meantime. Oates didn't know many people are displaced from the five apartment buildings involved.

Moviegoer Christopher Ramos today recalled the real-life horror of the midnight premiere of the latest Batman movie, "The Dark Knight Rises," in Aurora, Colo., as a gunman decked in riot gear set off smoke bombs and opened fire on the unsuspecting audience.

"People were running everywhere, running on top of me, like kicking me, jumping over me. And there were bodies on the ground," Ramos said. "I froze up. I was scared. I honestly thought I was going to die."

"The image in our heads is stuck in there. I still have the ticket right here and, honestly, I'm never going to forget this night at all. Because it was the first time I saw something that was real. Like a real-life nightmare that was there, not dreaming of," Ramos told ABC News today.

Witnesses in the movie theater said they saw smoke and heard gunshots that they thought were part of the movie until they saw Holmes standing in front of the screen, after entering from an emergency exit. Holmes methodically stalked the aisles of the theater, shooting people at random, as panicked movie-watchers in the packed auditorium tried to escape, witnesses said.

At one point the shooter exited the theater only to wait outside the doors and pick off patrons as they tried to exit, witness Jennifer Seeger told "Good Afternoon America."

"You just smelled smoke and you just kept hearing it, you just heard bam bam bam, non-stop. The gunman never had to reload. Shots just kept going, kept going, kept going," one witness told ABC News.

"I'm with coworkers and we're on the floor praying to God we don't get shot, and the gunshots continue on and on, and when the sound finally stopped, we started to get up and people were just bleeding," another theatergoer said.

The suspected shooter will face his first court appearance next week, according to district attorney Carol Chambers.

Holmes, originally of San Diego, moved to Aurora to pursue his Ph.D. at the University of Colorado medical center, living blocks from the hospital in an apartment that police say is now laced with explosives and being searched by HazMat teams.

Federal law enforcement sources told ABC News that Holmes bought a ticket to the movie, slipped out of the theater once it began and propped open the emergency exit before gathering his weapons and gear and coming back into the theater. Once inside, he opened fire.

A San Diego woman identifying herself as James Holmes' mother spoke briefly with ABC News this morning.

She had awoken unaware of the news of the shooting and had not been contacted by authorities. She immediately expressed concern that her son might have been involved.

"You have the right person," she said.

"I need to call the police," she added. "I need to fly out to Colorado."

The woman and her husband later released a statement saying their "hearts go out to those who involved in this tragedy and to the families and friends of those involved. We are still trying to process this information and we appreciate that people will respect our privacy."

The highly anticipated third installment of the Batman trilogy opened to packed auditoriums across the country at midnight showings this morning, and features a villain named Bane who wears a bulletproof vest and gas mask. Trailers for the movie show explosions at public events, including a football game. Though many moviegoers dressed in costume to attend the opening-night screening, police have made no statements about any connection between the gunman's motives and the movie.

Police in New York have intensified security around showings of the film throughout the five boroughs today, with Police Commissioner Ray Kelley saying that "as a precaution against copycats and to raise the comfort levels among movie patrons in the wake of the horrendous shooting in Colorado, the New York City Police Department is providing coverage at theaters where the 'The Dark Knight Rises' is playing."

The Paris premiere of the movie has been cancelled in the wake of the shootings. "Warner Bros. and the filmmakers are deeply saddened to learn about this shocking incident. We extend our sincere sympathies to the families and loved ones of the victims at this tragic time," the movie's producers said in a statement.

Witnesses watching movies in theaters next to the one where the shooting took place said bullets tore through the theater walls and they heard screaming.

"The suspect throws tear gas in the air, and as the tear gas appears he started shooting," said Lamar Lane, who was watching the midnight showing of the movie with his brother. "It was very hard to breathe. I told my brother to take cover. It took awhile. I started seeing flashes and screaming, I just saw blood and people yelling and a quick glimpse of the guy who had a gas mask on. I was pushed out. There was chaos, we started running."

One witness said she saw people dropping to the ground after the gunshots began.

"We were maybe 20 or 30 minutes into the movie and all you hear, first you smell smoke, everybody thought it was fireworks or something like that, and then you just see people dropping and the gunshots are constant," witness Christ Jones told ABC's Denver affiliate KMGH. "I heard at least 20 to 30 rounds within that minute or two."

A man who talked to a couple who was inside the theater told ABC News, "They got up and they started to run through the emergency exit, and that when she turned around, she said all she saw was the guy slowly making his way up the stairs and just firing at people, just picking random people.

"The gunshots continued to go on and on and then after we didn't hear anything ...we finally got up and there was people bleeding, there was people obviously may have been actually dead or anything, and we just ran up out of there, there was chaos everywhere."

Witnesses and victims were taken to Gateway High School for questioning.

Hundreds of police and FBI agents are involved in the investigation. A senior official who is monitoring the situation in Washington said that early guidance based on the early snapshot of this man's background indicated that this act does not appear to be linked to radical terrorism or anything related to Islamic terrorism.

Dr. Comilla Sasson, at the University of Colorado Hospital where many of the victims were taken, said they were operating on nine critical patients and have treated 22 in all. She called the hospital "an absolutely terrifying scene all night."

"The good news is that the 3-month-old has actually been discharged home and is in the care of their parents."

In a statement, President Obama said, "Michelle and I are shocked and saddened by the horrific and tragic shooting in Colorado. Federal and local law enforcement are still responding, and my 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."

For continuing coverage on "Tragedy in Colorado: The Batman Massacre," tune in to "World News," "20/20" and "Nightline."

Matthew Mosk contributed to this report.