- The suspected gunman booby-trapped his apartment, police say
- Attempts to enter the apartment are postponed until Saturday, police say
- Robots are sent in to get a better idea of what is inside, a source says
Aurora, Colorado (CNN) -- The one-bedroom apartment rented by the suspect in Friday's shooting rampage inside a suburban Denver movie theater appears to have been rigged with an array of sophisticated booby traps that one official described as "unique."
The law enforcement official said that video shot by robots shows at least a dozen "victim-initiated devices" -- none of which appear to have been equipped with timers -- inside the apartment. "You normally don't see this situation," the official said.
Authorities hope to enter Saturday the third-floor apartment of James E. Holmes, who is accused of killing 12 people early Friday and wounding scores more in Aurora, Colorado, Police Chief Daniel Oates said.
Robots may return Saturday to shoot more video and/or to retrieve samples from inside the 850-square foot apartment, the first law enforcement official said.
Suspect bought over 6,000 rounds of ammunition
James Holmes, 24, was identified by two federal law enforcement officers as the man who opened fire during a screening of "The Dark Knight Rises" at an Aurora, Colorado, theater early Friday. At least 12 people were killed, Police Chief Dan Oates said. 
Police break the apartment window of James Holmes, the suspect of a movie theater shooting Friday in Aurora, Colorado. 
An ambulance is parked outside. Of the wounded, at least 20 were being treated at the University of Colorado Hospital, said spokeswoman Jacque Montgomery. "They're arriving by police, by ambulance. Some are walking in," she said. 
Agents search the suspect's car outside the theater. 
People grieve during a vigil for victims behind the theater where a gunman opened fire on moviegoers in Aurora on Friday. 
A woman grieves during a vigil for victims behind the theater. 
A distraught woman is counseled by Pastor Quincy Shannon, left, of the New Hope Fellowship and an unidentified advocate in front of Gateway High School in Aurora, Colorado, where the families of the missing are meeting following the shooting at the Century 16 movie theater. 
Lin Gan wipes away her tears as her mother, Juan Gan, guides her to their car after meeting with counselors at the Gateway High School in Aurora on Friday. 
Lin Gan, of Aurora, Colorado, holds back tears as she speaks to reporters about her experience in the Century 16 theater on Friday. 
People embrace before a vigil for victims behind the theater where a gunman opened fire on moviegoers in Aurora on Firday. 
The car belonging to the suspect is removed from behind the theater where the shooting took place on Friday. 
Investigators work on evidence near the apartment of of James Holmes on Friday. 
Memebers of the Aurora Police Department. SWAT walk near the apartment of James Holmes. Police have Holmes,24, of North Aurora in custody. 
Television news crews gather in front of the home of Robert and Arlene Holmes, parents of 24-year-old mass shooting suspect James Holmes, in San Diego, California. on Friday. 
A popcorn box lies on the ground outside the Century 16 movie theatre. 
An NYPD officer keeps watch inside an AMC move theater where the film "The Dark Knight Rises" is playing in Times Square on Friday. NYPD is maintaining security around city movie theaters following the deadly rampage in Aurora, Colorado. 
Adariah Legarreta, 4, is comforted by her grandmother Rita Abeyta near the Century 16 Theater in Aurora. 
A cyclist and pedestrians pass a theater showing the latest Batman movie in Hollywood, California, on Friday. Warner Brothers said it was "deeply saddened" by Friday's massacre at a Colorado screening of "The Dark Knight Rises." 
Obama supporters observe a moment of silence for the victims at a campaign event at Harborside Event Center in Fort Myers, Florida, on Friday. 
Jessica Ghawi, an aspiring sportscaster, was one of the victims. 
A woman waits for news outside Gateway High School, a few blocks from the scene of the shooting at the Century Aurora 16. 
Aurora police chief Daniel J. Oates speaks at a press conference near the Century 16 Theater on Friday. 
Agents search the trash container outside the suspect's apartment in Aurora. 
A Federal ATF officer carries protective gear onsite at the home of alleged shooting suspect James Holmes. 
Obama speaks on the shootings at the event in Fort Myers. 
Moviegoers are interviewed at the Century Aurora 16. 
Officers gathered at the theater Friday. 
Investigators were a common sight at the theater Friday. 
Authorities gather at the shooting suspect's apartment building in Aurora. Police broke a second-floor window to look for explosives that the suspect claimed were in the apartment. 
Screaming, panicked moviegoers scrambled to escape from the black-clad gunman, who wore a gas mask and randomly shot as he walked up the theater's steps, witnesses said. 
University of Colorado Hospital spokeswoman Jacque Montgomery said that all of the wounded had injuries from gunshot wounds, ranging from minor to critical. 
A woman sits on top of her car near the crime scene. 
Police block access to the Town Center mall after the shooting. 
Witnesses told KUSA that the gunman kicked in an emergency exit door and threw a smoke bomb into the darkened theater before opening fire. 
What is believed to be the suspect's car is examined after the shooting. 
Repubican presidential candidate and former Massachusetts Gov. Mitt Romney delivers remarks regarding the shooting in an Aurora, Colorado, movie theater on Friday at a campaign event in Bow, New Hampshire. 
Photos: Colorado movie theater massacre 
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Victim shot in the neck, describes scene 
Shooting witness: Killer was stoic It was not clear whether authorities were planning to detonate any of the devices.
"Jars of black powder" and what appear to be "liquid accelerants" attached to the explosive devices are also inside Apartment 10, the official said. "He placed other chemicals to enhance fire/thermal effect of IEDs," the official added about Holmes' apartment.
"He has a level of expertise, not crude," the official said.
About 100 officials were to converge at the apartment building at 1690 Paris Street. Federal personnel flown here from out of state include bomb technicians from the Bureau of Alcohol, Tobacco, Firearms and Explosives and Explosive Ordinance & Disposal specialists.
Police evacuated five buildings Friday, including the one where Holmes lived, after he told them he had rigged his apartment with explosives.
"It is a very vexing problem how to enter that apartment safely. I personally have never seen anything like what the pictures show us is in there," Oates told reporters Friday night.
"I see an awful lot of wire, trip wires, jars full of ammunition, jars full of liquid and ... things that look like mortar rounds."
Holmes told police shortly after he was apprehended in the rear parking lot of the movie theater that he had rigged his apartment, Oates said.
Gun-control, gun-rights groups ready for renewed debate after shooting
Police arrived at Holmes' apartment to find "techno-music" blaring from the bedroom, according to a law enforcement source, who spoke on condition of anonymity.
The music was on a timer and apparently started once he left for the movie theater, said the source, who was not authorized to release details of the investigation to the media.
Oates said it could take days to work through the apartment safely.
While authorities did not say how many residents were evacuated from nearby buildings, the number is estimated to be in the hundreds.
Authorities began Friday night to allow families in four of the five evacuated buildings to return to their residences to retrieve personal items, such as medication, identification cards and clothing.
Opinion: When will America wake up to gun violence?
A shelter was set up at Aurora Central High School for those forced from their apartments.
Were you there or have thoughts about the shooting? Let us know on CNN iReport.
CNN's Susan Candiotti and Chelsea J. Carter contributed to this report.
