AURORA, Colo. -- Authorities on Saturday began the intricate process of disarming booby traps in the apartment of the suspect behind the Colorado movie theater rampage, hoping to find clues inside to the motive for the shootings without causing an explosion that could destroy key evidence.
Scores of law enforcement officials, including bomb squad technicians and dozens of federal agents, removed one trip wire and one explosive device inside James Holmes' apartment Saturday, and "other devices" are in there, Aurora police Sgt. Cassidee Carlson said.
"We have been successful in defeating the first threat," Carlson said. The traps were meant to kill the first people entering the apartment, she said.
The shooter, 24, was arrested early Friday outside the suburban Denver theater with high-powered weapons and ammunition and charged with the rampage that killed 12 and injured 58 during the midnight showing of the new Batman movie, "The Dark Knight Rises."
Makeshift memorials sprang up for the victims, including a U.S. navy sailor, an aspiring sportscaster and a man celebrating his 27th birthday. In his Saturday radio address, President Barack Obama urged Americans to pray "for the victims of this terrible tragedy, for the people knew them and loved them, for those who are still struggling to recover."
Seven of the wounded remained in critical condition on Saturday, some with injuries that could be permanent, a trauma surgeon said.
Police have been unable to enter the shooter's apartment after learning it had been booby-trapped with trip wires and possible explosives, and evacuated several buildings around it.
Experts entered the apartment and began to disarm the trip wires one by one to render them harmless, hoping not to detonate anything that could eliminate evidence against the suspect or information about a motive.
"We don't want to lose evidential value," Carlson said.
About 30 ammunition shells and up to 30 other devices in the apartment also need to be disarmed, she said.
"A controlled detonation or another triggering mechanism" might be required, she said.
Police grimly went door to door late Friday with a list of victims killed in the worst mass shooting in the U.S. in recent years, notifying families who had held out hope that their loved ones had been spared.
The victims included 23-year-old Micayla Medek, said Anita Busch, the cousin of Medek's father. The family took the news hard, but knowing her fate after waiting without word brought them some peace, Busch said.
"I hope this evil act, that this evil man doesn't shake people's faith in God," she said.
Besides Medek, relatives confirmed that Alex Sullivan and Jessica Ghawi were among those killed, Sullivan on his 27th birthday, as they gathered for a midnight showing of the newest Batman movie "The Dark Knight Rises."
Aurora Police Chief Dan Oates said the shooter used a military-style semi-automatic rifle, a shotgun and a pistol to open fire on the unsuspecting theater-goers. He had bought the weapons at local gun stores within the last two months. He also recently purchased 6,000 rounds of ammunition over the Internet, the chief said.
The suspect's stellar academic record, apparent shy demeanor and lack of a criminal background made the attack even more difficult to fathom.
It also wasn't known why the suspect chose a movie theater to stage the assault, or whether he intended some twisted, symbolic link to the film's violent scenes.
The Batman movie, the last in the trilogy starring Christian Bale, opened worldwide Friday with midnight showings in the U.S. The plot has the villain Bane facing Bale's Caped Crusader with a nuclear weapon that could destroy all of fictional Gotham.
In New York City, Police Commissioner Raymond Kelly said: "It clearly looks like a deranged individual. He has his hair painted red. He said he was the Joker, obviously the enemy of Batman."
Oates would not confirm that information, but did say he spoke to Kelly. Asked whether the shooter had makeup to look like the Joker, Oates said: "That to my knowledge is not true."
Near the entrance to the theater's parking lot, a makeshift memorial of 12 candles sat in a row alongside piles of flowers, and dozens of other memorials cropped up around Denver. Up the hill from the theater, about 20 pastors led a vigil for 350 people, some hugging and crying. A sign read, "7/20. Gone Not Forgotten."
An emotional Gov. John Hickenlooper said earlier Friday that people would not be defined by the tragedy.
"We are clear that we are going to rise back and lift ourselves above this," he said.
A federal law enforcement official said the shooter bought a ticket to the movie, went into the theater as part of the crowd and propped open an exit door as the movie was playing. The suspect then donned protective ballistic gear and opened fire, the official said, speaking on condition of anonymity because he was not authorized to discuss the investigation.
Authorities said the suspect shot scores of people, picking off victims who tried to flee. At least one person was struck in an adjacent theater by gunfire that went through the wall. Adding to the terror and chaos were two gas canisters thrown by the suspect that filled the theater with smoke.
Tanner Coon, a 17-year-old Aurora resident who was watching the film with two friends, said he first thought the gunshots were firecrackers. When he realized what was happening, he ducked between seats and waited for the shooter to bark demands.
"When is he going to start telling us what to do? When is this going to become a hostage situation?" Coon said.
When the firing ended, Coon said he started running up the row but slipped in blood and fell on a woman who was lying on the ground. He tried shaking her, he said, but she didn't respond, so he left her behind and ran from the theater.
The shooting was the worst in the U.S. since the Nov. 5, 2009, attack at Fort Hood, Texas. An Army psychiatrist was charged with killing 13 soldiers and civilians and wounding more than two dozen others. It was the deadliest in Colorado since the 1999 attack at Columbine High School, where two students killed 12 classmates and a teacher and wounded 26 others before killing themselves.
Police released a statement from his family Friday that said, "Our hearts go out to those who were involved in this tragedy and to the families and friends of those involved."