New details are emerging about the shooting at an Aurora movie theater that killed 12 people and injured 58 more.
7NEWS has learned that the first responding officers mistook the suspected gunman as one of their own.
James Holmes was arrested at the back of the Aurora Century 16 movie theater about 12:40 a.m. as he was leaving the theater.
Holmes was dressed in black and was wearing full tactical gear, including a ballistics helmet, a ballistics vest, a groin protector, throat protector, tactical gloves and other gear, police said.
He was well armed with an AR-15 .223-caliber rifle, a Remington 12-gauge shotgun and a .40-caliber Glock handgun, police said. Another .40-caliber Glock handgun was found in the suspect's white Hyundai behind the theater.
Aurora Police Chief Dan Oates said Holmes came with a full arsenal.
"In the last 60 days, he purchased four guns at local metro gun shops, and through the Internet, he purchased more than 6,000 rounds of ammunition, more than 3,000 rounds of .223 for the assault rifle, 3,000 rounds of .40-caliber ammunition for the two Glocks in his possession and 300 rounds for the 12-gauge shotgun," Oates said. " Also through the Internet, he purchased multiple magazine for the .223-caliber assault rifle, including one 100-round drum magazine which was recovered from the scene."
The drum could allow a shooter to fire 50 to 60 rounds in a minute -- even as a semi-automatic, Oates said.
ABC News reported that Holmes identified himself as the Joker, and that his hair had been dyed to resemble the villain played by Heath Ledger in "The Dark Knight." Police declined to comment on that detail.
7NEWS has learned Holmes legally bought the firearms at a Bass Pro Shop and Gander Mountain Guns within the last several months. The first gun was bought in May.
Oates gave no motive for the attack. The FBI said there was no indication of ties between Holmes and any terrorist groups.
Investigators said they have no idea how many rounds were fired, but that it was many.
One source believed the ammo drum for the AR-15 had jammed sometime during the shooting.
Sources describe an eerie scene with dying and wounded people on the floor, strobe lights flashing through the smoke, screaming sirens and the Batman movie playing in the background.
The incident started with Holmes in the theater watching a movie for a few minutes. Witnesses said he left and returned dressed in the body armor and tactical gear, according to sources.
He threw what appeared to be tear gas grenades and began firing three weapons according to sources.
Holmes then exited the theater, where he was confronted by at least two officers.
While Vicodin comes in pills of 500 mg and up, the source indicated that police were told Holmes took 100 mg of Vicodin.
Moviegoers said they did not know what was happening when they heard a hissing sound and smelled smoke. Some thought the attack was part of the movie, since it occurred during a battle scene about 20 minutes into the movie. Then they saw a silhouette of a person in the smoke at the front of the theater near the screen, pointing a gun at the crowd.
"There were bullet (casings) just falling on my head. They were burning my forehead," Jennifer Seeger said, adding that the gunman fired steadily except when he stopped to reload.
Seeger said she was in the second row, about 4 feet from the gunman, when he pointed a gun at her face. At first, "I was just a deer in headlights. I didn't know what to do," she said. Then she ducked to the ground as the gunman shot people seated behind her.
She said she began crawling toward an exit when she saw a girl about 14 years old "lying lifeless on the stairs." She saw a man with a bullet wound in his back and tried to check his pulse, but "I had to go. I was going to get shot."
Many of those injured or killed were young adults, teens or kids. The victims range in age from 4 months to 45 years old. The 4 month old has been discharged and is doing well, a hospital spokeswoman said.
Police said 911 calls started coming in 12:39 a.m. Police said officers were on the scene with 60 to 90 seconds and immediately arrested the suspect.
Victims were rushed to hospitals in police cars by responding officers because there were not enough ambulances.
Ten people died in the theater, two more died at the hospital, Aurora police said. The bodies were not removed from the theater until late Friday afternoon.
Witnesses told 7NEWS that the gunman opened fire in Theater 9, but bullets also pierced the wall with the adjacent Theater 8 injuring moviegoers.
Witness Shayla Roeder said she saw a young teenage girl on the ground bleeding outside the theater.
"She just had this horrible look in her eyes .... We made eye contact, and I could tell she was not all right," Roeder said.
The Aurora police response was swift, since police headquarters is less than a mile away from the theaters. More than 250 police officers from across the metro area -- from Brighton to Jefferson County -- were also called out to respond to the mass shooting.
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