At least 12 moviegoers in Aurora, Colo., died early today when a heavily armed gunman opened fire at the midnight premiere of the new Batman film, The Dark Knight Rises. A 6-year-old girl was among the dead, and 59 people were wounded.

The suspect, identified as James Eagan Holmes, 24, a San Diego native, was arrested in the parking lot behind the Century 16 multiplex wearing tactical body armor and a gas mask. Police recovered a military-style assault rifle, a shotgun and two pistols.

Police say his Aurora apartment is "extensively booby-trapped" with chemicals and trip wires.

Update at 8:16 p.m. ET: The Medical Center of Aurora says it received 18 of the wounded and injured. One remains in the emergency room and seven were admitted, with two in critical condition and five listed as stable.

Family and friends of patients can call 303-873-5292 for information.

Swedish Medical Center also received victims, but it has not posted any updates on its "breaking news pages." The family-support line is 303-788-5000.

Update at 7:50 p.m: A law enforcement source tells CNN that Holmes' booby-trapped apartment is so intricately rigged and dangerous that robots may be used to disarm the flammable or explosive materials.

A decision about entering the apartment isn't expected until tomorrow.

"There's so much circuitry and collapsing circuits, it's a difficult process," the source told CNN.

Robots were sent inside earlier today to gather video.

At an evening news briefing, Aurora Police Chief Dan Oates said that the dwelling is booby-trapped with "various incendiary and chemical devices and trip wires," and that the operation could take days.

Four surrounding buildings were evacuated, Oates said.

Fire trucks that had stood by all day were withdrawn tonight.

Update at 7:28 p.m. ET: The director of The Dark Knight Rises, Christopher Nolan, has released a statement:

Speaking on behalf of the cast and crew of "The Dark Knight Rises", I would like to express our profound sorrow at the senseless tragedy that has befallen the entire Aurora community. I would not presume to know anything about the victims of the shooting but that they were there last night to watch a movie. I believe movies are one of the great American art forms and the shared experience of watching a story unfold on screen is an important and joyful pastime. The movie theatre is my home, and the idea that someone would violate that innocent and hopeful place in such an unbearably savage way is devastating to me. Nothing any of us can say could ever adequately express our feelings for the innocent victims of this appalling crime, but our thoughts are with them and their families.

Update at 6:36 p.m. ET: Holmes invoked his right to legal counsel shortly after his arrest, a Colorado law enforcement official tells USA TODAY's Kevin Johnson. It's not immediately clear how much information he has provided about the booby traps found at his Aurora apartment.

It's not known whether he he has retained or been assigned a lawyer.

Earlier, citing a law enforcement official briefed on the investigation, the Associated Press wrote that Homes "is not talking to investigators."

Police have found jars of chemicals connected to trip wires in his apartment at 1690 Paris Street.

The Colorado official told Johnson that authorities believe Holmes plotted the attack for some time.

"The place was rigged to blow,'' the official said.

A neighbor told the Denver Post he called 911 about 12:30 a.m. today to report loud, techno music blaring from Apartment 10, where Holmes lived. One song appeared to be looping.

Holmes' downstairs neighbor, a 20-year-old biology student, said she went upstairs and knocked on his door, which was unlocked. No one answered, but she decided not to enter.

She said the music stopped almost at exactly 1 a.m.

Investigators still do not have a motive.

Update at 6:23 p.m. ET: Authorities have begun removing the bodies of the 10 people who were shot dead in the theater, theDenver Post is reporting.

Update at 5:41 p.m. ET: Representatives from the two gunshops where Holmes bought four weapons have issued statements, USA TODAY's Kevin Johnson says.

Larry Whitely, a spokesman for Bass Pro Shops in Denver, where two guns were bought, called the shootings "an unspeakable tragedy.''

"Based on the records we have reviewed, personnel in our Denver store correctly and fully followed all federal requirements with respect to the sale of one shotgun and one handgun to the individual identified in this incident,'' Whitely said. "Background checks, as required by federal law, were properly conducted, and he was approved.''

"Again, our hearts go out to the victims and their families,'' he said.

Jess Myers, a spokesman for Gander Mountain stores, where the other two guns were bought, said the company "fully cooperates with law enforcement in criminal investigations like the one regarding the tragic events in Colorado."

"We operate in strict compliance with all local, state and federal laws regarding firearms ownership and are fully cooperating with this on-going investigation,'' Myers said. "As long-time business owners in Aurora, this community is our home and the home to many of our associates and customers. We send our thoughts and prayers out to those affected. In respect for the victims of this tragic crime and their families, we will have no further comment in this matter.''

Update at 5:29 p.m. ET: AMC Theatres has banned costumes, masks or fake weapons, and is beefing-up its security at its 346 theaters in the United States and Canada.

"We will not allow any guests into our theatres in costumes that make other guests feel uncomfortable and we will not permit face-covering masks or fake weapons inside our buildings," a company statement says.

AMC, the second largest movie theater chain in North America, would not disclose its new security measures.

The statement says the company "is deeply saddened by the Aurora tragedy. Movie going is part of our social fabric and this senseless act shakes us to our core."

Update at 4:34 p.m. ET: Warner Bros. has pulled its trailer for Gangster Squad, which includes men shooting into a movie theater audience, from all The Dark Knight Rises screenings, the Apple trailer site and YouTube, a studio executive tells USA TODAY. The studio has also pulled all advertising for The Dark Knight Rises from the Aurora, Colo., area.

Update at 4:24 p.m. ET: A federal law enforcement official tells USA TODAY's Kevin Johnson that the four weapons were purchased in May, June and July at Denver and Aurora-area gun shops. Investigators have recovered at least one video from a store security camera recording a purchase.

The assault rifle was traced to a Gander Mountain gun store in Thornton, Colo., and the Remington shotgun and one of the Glock handguns were bought at a Bass Pro Shop in Denver. The second Glock was purchased at Gander Mountain store in Aurora.

The official, who was not authorized to speak publicly, said a cache of ammunition was recovered in the suspect's car and used magazines were found discarded in the theater.

Update at 4:15 p.m. ET: Holmes was armed with an AR-15 assault rifle, a 12 gauge shotgun and a Glock .40 caliber handgun, said Aurora Police Chief Dan Oates. A .40 gauge handgun was found in his car, which was parked just outside the rear entrance to the cinema.

He bought a ticket to the midnight show, the first for the latest Batman movie, and entered the theater with the crowd, a U.S. law enforcement official tells the Associated Press. Holmes then apparently propped open an exit door after the movie started, donned protective gear and then started shooting.

Another source tells AP the assault rifle was equipped with a high-capacity, drum-style ammunition clip.

Update at 4:11 p.m. ET: Of the 59 wounded, 11 are listed in critical condition.

The youngest victim was believed to be a 4-month old infant was treated for non-life threatening injuries and released.

Update at 4:08 p.m. ET: The Pentagon says that three service members were among the injured and that one is unaccounted for, NBC News reports.

Update at 3:58 p.m. ET: Warner Bros. is withdrawing two TV ads for The Dark Knight Rises, Bloomberg News is reporting, citing sources.

Update at 3:52 p.m. ET: Holmes "said he was the Joker, enemy of Batman," New York City Police Commissioner Raymond Kelly said after conferring with the Aurora, Colo., chief, the New York Daily News is reporting. "He had his hair painted red."

Update at 3:44 p.m. ET: The flag at the U.S. Capitol has been lowered to half-staff "as mark of respect for victims in Aurora, Colorado."

Update at 3:37 p.m. ET: Three research buildings at the University of Colorado where Holmes may have worked have been been evacuated and all nonessential staff sent home, USA TODAY's Jefferson Graham reports.

"We want to make sure everything is safe for our people," says university spokeswoman Erica Matich.

Original post by Douglas Stanglin:

Update at 10:23 a.m. ET: Colorado Gov. John Hickenlooper says the attack in Aurora "is not only an act of extreme violence, it is also an act of depravity," CBS News reports.

Update at 10:20 a.m. ET: President Obama has spoken to the mayor of Aurora about the tragic shootings.

Update at 9:55 a.m. ET: Joseph Soto, 18, says he was in an adjacent theater when shots rang out, USA TODAY's Trevor Hughes reports. He says theatergoers were confused at first because there was an on-screen gunbattle happening at the time. Rounds from Theater 9 came through the wall into Theater 8, he says. "We all thought it was a joke," he says. "We found out it wasn't a joke."

Update at 9:54 a.m. ET: CNN reports that police searching the suspect's apartment have not found any explosives.

Update at 9:51 a.m. ET: USA TODAY's Trevor Hughes quotes a Red Cross spokesperson in Colorado as advising residents in the Aurora area to update their Facebook and other social media accounts to reassure friends and relatives that they are safe in the wake of the shootings. "People don't know how close you were, so help alleviate that anxiety," Patricia Billinger says.

Update at 9:44 a.m. ET: President Obama has canceled his campaign stops in Florida and headed back to Washington in the aftermath of the Colorado shootings, according to a statement from the campaign, USA TODAY's blog The Oval reports.

Update at 9:33 a.m. ET: USA TODAY's Gregg Zoroya reports from the Pentagon that the Army has checked its databases and finds no evidence that the suspect had served in the U.S. Army. The Marines, likewise, say they have no information on the shooting suspect.

Update at 9:29 a.m. ET: Police in Aurora surrounded the suspect's apartment and are searching it for possible explosives. KUSA-TV reports that the suspect indicated that he had explosive material at the site.

Update at 9:26 a.m. ET: USA TODAY's Kevin Johnson says federal law enforcement officials confirmed that the suspect is James Holmes. The officials say the suspect "was not on anybody's radar" and apparently did not have a record. The sources say there are 100 federal agents involved in the case, including bomb experts.

Update at 8:58 a.m. ET: KUSA-TV reports that a 3-month-old baby wounded in the Aurora shootings has been treated and released from the hospital. Clarifying at 9:10 a.m.: KUSA-TV did not report that the child had been wounded, rather that the infant had been hospitalized, checked out and released.

LISTEN: 911 calls from the Colo. shootings

Update at 8:54 a.m. ET: The Hollywood Reporter says Warner Bros. has canceled its red carpet premiere tonight in Paris of The Dark Knight Rises and has issued this statement:

Warner Bros. is 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.

Update at 8:39 a.m. ET: The FBI tells NBC News that the suspect was driving a car with Tennessee license tags but had been living locally.

Update at 8:35 a.m. ET: CNN quotes Frank Fania, a police spokesman, as saying the gunman "did not resist. He did not put up a fight."

Fania says police seized a rifle and a handgun from the suspect, and another gun was found in the theater, CNN reports.

Update at 7:51 a.m. ET: NBC News quotes two federal officials as identifying the shooting suspect as James Holmes, who was born Dec. 13, 1987.

Update at 7:51 a.m. ET: KUSA-TV says Aurora police revised the number of casualties in the Aurora shooting and say there were approximately 50 victims with at least 12 dead. MSNBC also reports that police lowered the death toll to 12.

Update at 7:41 a.m. ET: Denver's Fox31 reports that the gunman opened fire in Theater No. 9 of the Century 16 Movie Theater. The bullets pierced the wall and hit some victims in Theater No. 8.

Update at 7:39 a.m. ET: The FBI says there is no indication that the Aurora shootings are connected to terrorism, the Associated Press reports.

Update at 7:37 a.m. ET: Mitt Romney, the GOP presidential candidate, says in a brief statement, "Ann and I are deeply saddened, praying for families and loved ones of the victims."

Update at 7:36 a.m. ET: Here is the full statement from President Obama:

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 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. As we do when confronted by moments of darkness and challenge, we must now come together as one American family. All of us must have the people of Aurora in our thoughts and prayer as they confront the loss of family, friends and neighbors, and we must stand together with them in the challenging hours and days to come.

Update at 7:25 a.m. ET: President Obama says he is "shocked and saddened" by the "horrific and tragic" Colorado shooting. The president, who spent the night in Florida while campaigning, was notified of the shootings at 5:26 a.m. ET by John Brennan, assistant to the president for Homeland Security and Counterterrorism, according to the White House.

Original report: Here are some eyewitness reports of the shooting at the Aurora, Colo., theater:

KUSA-TV's Jeremy Jojola interviewed two eyewitnesses who were in the theater when the shooting started.

"I saw a man walk in through the exit," one eyewitness told Jojola. "[He] looked like he had a gas mask on."

The witnesses said he threw two gas canisters into the theater after busting down the door. The witnesses said no one reacted at first - thinking he was a stunt for the movie.

"He looked so calm when he did it," a witness said. "It was, like scary. He waited for both the bombs to explode before he did anything. Then, after both of them exploded, he began to shoot."

The witnesses said the gunman first fired into the air, then started shooting toward the people. "He had no specific target. He just started letting loose," one witness said.

Both witnesses said the gunman didn't say a word.

"Honestly, I thought I was gonna get shot," a witness said. "I thought there was no way I was going to get out of there without getting shot."