Updated 8:54 PM ET
(CBS/AP) AURORA, Colo. - A gunman clad in body armor and wearing a gas mask opened fire on moviegoers at a midnight showing of the latest Batman movie Friday, killing 12 and injuring dozens more in one of the deadliest mass shootings in recent U.S. history.
The violent and chaotic scene erupted at about 12:30 a.m. local time as the suspected gunman, identified as 24-year-old James Holmes, stood at the front of one of the Century 16 theaters at the Aurora Mall where "The Dark Knight Rises" was playing. Witnesses reported that the gunman entered the theater through an emergency exit door and authorities said he threw two gas canisters before opening fire.
"Then it was a blur," Spenser Sherman told "CBS This Morning" said. "Then I heard a couple gunshots."
"I thought it was part of the movie, like a fun little prank - that it would be over in a few seconds. It obviously wasn't."
She said she only saw a silhouette of the suspect, and that the gunman said nothing.
Aurora Police chief Dan Oates had earlier said a total of 71 people were shot, including the dead. Of the 59 people wounded, some were critically injured, though Oates couldn't give an exact figure.
Jennifer Seeger told CBS station KCNC the suspect first fired up towards the ceiling, as if to scare people, and then started spraying the audience. He pointed the gun directly at her; she ducked. "He had a gas mask on so I couldn't see his face," she said. "All I smelled was gunpowder in the air, and gas was getting to me."
The suspect marched up the aisle in the stadium-style theater, picking off those who tried to flee, witnesses said. Authorities said he hit 71 people. One of them was struck in an adjacent theater by gunfire that went through the wall.
"He would reload and shoot and anyone who would try to leave would just get killed," said Seeger, adding that bullet casings landed on her head and burned her forehead.
Authorities gave no motive for the attack. The FBI said there was no indication of ties to any terrorist groups.
Holmes wore body armor, used an assault rifle, a shotgun and a Glock handgun, Oates said. He said investigators are confident the gunman acted alone. A second Glock handgun was found in Holmes' car. All the guns were purchased legally between May 22 and July 6 at three Colorado stores, CBS News correspondent Bob Orr reports.
FBI agents and police also discovered Holmes' apartment was booby trapped. Authorities evacuated five buildings as they determined how to disarm flammable and explosive material.
"It's something I've never seen before," Oates said.
CBS News has learned that some loud music blaring from Holmes' apartment around the time of the attack allegedly was designed to draw a noise complaint from a neighbor, thus luring police into his residence, sparking a firebomb and diverting resources from the movie theater.
A federal law enforcement official said the suspect bought a ticket and went into the theater as part of the crowd. He is believed to have propped open an exit door as the movie was playing, put on protective ballistic gear and opened fire. The official spoke on the condition of anonymity to discuss the ongoing investigation.
Federal law enforcement officials said there is no indication it is terrorism-related.
Authorities started to remove the bodies from the theater on Friday afternoon. Officials wheeled a black bag on a stretcher out of the front entrance, placing it in the back of a minivan. Ten people died in the theater, while two others died from their injuries later.
Aurora police say victims are still being identified and not all the families have been notified.
Jessica Ghawi, a sports blogger also known as Jessica Redfield, is among the dead, her brother confirmed.
Jordan Ghawi told The Associated Press his sister's death comes as a "complete and utter shock."
Ghawi recently wrote of leaving a Toronto mall moments before a June 2 shooting that left one dead and seven injured.
Jessica Ghawi began screaming when she was shot, and the man with her tried to calm her and stop the bleeding, according to Jordan Ghawi.
The man was then shot, but he continued attending to Jessica Ghawi's wound before he realized she had stopped screaming, Jordan Ghawi stated. The man said Jessica Ghawi had been shot in the head.
Some of the injured were children, with the youngest a 3-month-old baby who has been released from treatment. Victims were being treated for chemical exposure apparently related to canisters thrown by the gunman.
The Pentagon said three military members - one sailor and two airmen - were wounded in the incident. Another sailor remained unaccounted for. Aurora is home to a large Defense Department satellite intelligence operation at Buckley Air Force Base.
The nature of the attack suggests it was well planned. The suspect's vehicle was parked at the rear of the complex, near the emergency exit where he was reported to have entered from.
Those who knew Holmes described him as a shy, intelligent person raised in California by parents who were active in their well-to-do suburban neighborhood in San Diego. Holmes played soccer at Westview High School and ran cross-country before going to college.
On Friday morning, police escorted Holmes' father, a manager of a software company, from their home while his mother, a nurse, stayed inside, receiving visitors who came to offer support. Holmes also has a younger sister.
"As you can understand, the Holmes family is very upset about all of this," Lt. Andra Brown, the San Diego police spokeswoman, told reporters in the driveway of the family home. "It's a tragic event and it's taken everyone by surprise. They are definitely trying to work through this."
Police released a statement from his family that said: "Our hearts go out to those who were involved in this tragedy and to the families and friends of those involved."
There have been no indications so far that Holmes had any run-ins with the law before Friday.
Tom Mai, a retired electrical engineer, said Holmes was a "shy guy" who came from a "very, very nice family."
Holmes graduated from University of California, Riverside, in the spring of 2010 a bachelor's degree in neuroscience, a school spokesman said. Mai said the mother told him Holmes couldn't find a job after earning a master's degree and returned to school.
In 2011, he enrolled in the Ph.D. neuroscience program at the University of Colorado-Denver but was in the process of withdrawing, a university spokeswoman said.
Holmes lived in an apartment in Aurora, and FBI agents and police who went there discovered it was booby-trapped when they used a camera at the end of a 12-foot pole to look inside.
It was 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 more than two dozen others wounded.