FBI agent, Jim Yacone, said, "This was certainly challenging". Yacone then confirmed the discovery of sophisticated explosive devices, and how they had to use a robot to disarm a trip wire and the primary bomb.
"The threat has not been completely eliminated," Yacone said. He added that "an extensive amount of evidence is in the process of being collected."
According to bomb techs, 30 softball-sized, improvised explosives were found in the Aurora apartment of James Holmes, the suspect in the killing of 12 people and wounding of 58 others at the movie screening of the new Batman movie on Thursday night.
The FBI confirmed that the most dangerous booby-trap was connected to the front door of the apartment. Anyone who had directly opened the door would have been seriously injured or even killed.
The Aurora police department said that a controlled detonation was successfully performed inside the apartment, which can be heard in the above video. Police used robots to examine the suspect's residence without putting officers’ lives in danger and they plan to detonate the other devices remotely, rather than try to defuse them.
They plan to remove other explosive items in the apartment, including around 30 shells, that will be placed in sand trucks and taken to a disposal site.
While the apartment was being accessed, five nearby buildings were evacuated for safety.
According to Aurora police chief Daniel Oates, the apartment was booby-trapped with various chemical and incendiary devices connected to trip wires. Oates added that the explosives are so complex, "police could be on the scene for hours or days."
Oates also said Holmes has been preparing the attack for months.
"We've become aware that he had a high volume of deliveries to both his work and home address. We think this explains how he got his hands on the magazine, ammunition," he said. "We also think it begins to explain how he got the materials he had in his apartment.
"What we're seeing here is evidence of some calculation and deliberation," he added.
A special report video detailing and discussing the shooting suspect can be viewed here.
The apartment building where Holmes lived is in a lower-income area located about four miles from where the shootings took place during a midnight premiere of the Batman movie "The Dark Knight Rises". A memorial site for the victims has now been created behind the theater.
In the latest media update, all the explosives have now been disposed of safely. See video above.