AURORA, Colo. (CBS4) – A terrifying shooting at an Aurora movie theater overnight left 12 people dead and 58 others injured.

The shooting happened at about 12:30 a.m. at the Town Center in Aurora at the Century 16 theater on East Alameda Avenue. Reports first came in that there were explosions in the theater showing the new Batman movie “The Dark Knight Rises.” Shots then rang out, and a frantic scene followed.

Police said a gunman with a gas mask on and dressed in black shot and killed dozens and dozens of people. Authorities say the suspect, James Holmes, 24, killed 10 people inside the theater complex and that three others died after they were taken from the scene.

Authorities arrested Holmes at the back of the building. They say he had a rifle, a handgun and that another gun was located in the theater.

“Witnesses tell us he released some sort of canister. They heard a hissing sound and some gas emerged and the gunman opened fire,” Chief Dan Oates said.

Officials at one hospital confirmed that some of their patients had to be treated for chemical exposure. They went through that hospital’s decontamination process and were released.

The midnight showing of the heavily hyped third movie in the current Warner Bros. Batman franchise had just started when the violence began. Donovan Tate and his girlfriend escaped from the packed theater.

“There was this one guy on all fours crawling. There was this girl spitting up blood. There were bullet holes in some people’s backs, in some people’s arms. There was one guy who was just stripped down to his boxers. It looked like he had been shot in the back or something,” Tate told CBS4.

Jennifer Seeger was in the theater and thought it was a theatrical thing at first when the suspect came in the theater covered with black clothes, a vest and wearing a gas mask.

“I thought he was just doing it as part of the show to add some pizzaz or something,” said Seeger, who dove to the ground and managed to avoid getting hurt. He didn’t say anything he just took a gas can that was filled with gas, he took the cap off and threw it and it exploded everywhere. At that point people thought it was an effect so they didn’t think anything and then he shot his first shot into the ceiling and that made everyone scatter. It was mass pandemonium at that point.”

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Aurora police said victims were taken to six different hospitals, with 23 going to University of Colorado Hospital and 15 to The Medical Center of Aurora. They wrote in a news release that “many were rushed immediately to hospitals in police cars by responding officers. The injured and dead include a wide age range.”

University of Colorado Hospital spokeswoman Comilla Sasson said nine people were critical condition in their emergency room.

“At 1 a.m. we received notice that there had been a shooting in the area and then at about 1:15 a.m. we started having patients pouring in via police cars, ambulances private car,” Sasson said. “Then we activated our disaster protocol. So we had folks from all parts of the hospital coming in to help us, coming in specifically for this tragedy.”

The Medical Center of Aurora took in 15 patients after the shooting, 12 of whom had gunshot wounds. Those people ranged in age from 17 to 31. Six patients were taken to Denver Health Medical Center and three of those patients were treated and released.

A three-month-old was among the dozens who were hurt, but the baby was treated and released from the hospital.

Witnesses and people who were evacuated from apartments nearby were being taken to Gateway High School at 1300 S. Sable Blvd. for interviews and also to reunite with friends and family. RTD provided buses that were used to move those people back and forth from the scene of the shooting to the school.

Holmes is an Aurora resident and a graduate student in neurosciences at the medical school at the University of Colorado Aschutz Medical Campus who was was in the process of withdrawing. The car police say he used was located behind the movie theater. His apartment in Aurora at Peoria and 17th also was the site of an extensive police operation on Friday.

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The incident is one of the worst mass shootings in the United States since 32 people were killed in 2007 on the Virginia Tech campus in Blacksburg, Va. In 1999, 13 people were killed in the Columbine High School massacre that happened about 25 miles southwest of Friday morning’s attack.

“This is not only an act of extreme violence, it is also an act of depravity,” Gov. John Hickenlooper said in a prepared statement. “It is beyond the power of words to fully express our sorrow this morning. Our prayers and condolences go first to the families of those killed, and we share the grief of everyone affected by this senseless event. We appreciate the swift work by local, state and federal law enforcement. Coloradans have a remarkable ability to support one another in times of crisis. This one of those times.”

Many other elected officials, as well as celebrities, shared similar statements on Friday. Whoopi Goldberg said “We’ve got to stop looking for reasons here. There is no reason. Only irrational acts by irrational people. All we can do is try to bring comfort.”

Warner Bros., the studio behind “The Dark Knight Rises,” issued a statement Friday morning: “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.” (Full Story on CBSLosAngeles.com)

Warner Bros. also canceled the Paris Premiere screening of the film and all interviews with the cast and crew scheduled for Friday.

Locally, major movie theater chains in the Denver metro area told CBS4 that all scheduled screenings of “The Dark Knight Rises” would go on as planned.

Cinemark USA, the company that owns the Century 16 Theater, said they are working with police in the investigation. Cinemark owns 298 theaters across the country and four in Colorado.

“Cinemark is deeply saddened about this tragic incident. Our thoughts and prayers are with the victims, their families and loved ones, our employees, and the Aurora community,” the company said. “We are grateful for the quick and professional reaction of all local law enforcement and emergency responders.

In New York City, Mayor Michael Bloomberg ordered NYPD officers to increase patrols around theaters in the five Boroughs showing the film in order to avoid any possible copycat shootings and to put the moviegoing public at ease.

Bloomberg also had strong words for both men running for the office of President of the United States: “You know, soothing words are nice,” Bloomberg said, “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.”