Police did not rule out Saturday a "controlled detonation" in the booby-trapped apartment of the suspect in the Denver movie-theater massacre that left 12 people dead.

A spokesperson for the police department of Aurora, a town near Denver where the shooting occurred and where the suspect's apartment is located, said Saturday that a "controlled detonation" might be necessary because of the complex setup of tripwires and explosives that James Holmes, the 24-year-old suspect in the bloodbath, laid in his home.

The agent could not say when such a measure might be taken, but added that police will try to enter the apartment in the next hour to garner further information and possible evidence.

The attack, the worst in the United States since the Virginia Tech mass murder of 33 students in 2007, occurred in the wee hours Friday at the 16-theater Century multiplex during the premiere of "The Dark Knight Rises" from the Batman saga, attended by hundreds of people, many of them children.

Agents including those from the FBI and the Bureau of Alcohol, Tobacco, Firearms and Explosives, or ATF, have been studying the situation inside the suspect's apartment with robots and cameras, and have found tripwires, piles of ammunition, possible explosive devices and containers with liquid inside.

The spokesperson said that police are proceeding with caution due to the extreme danger of the operation and will gather all possible evidence if they finally decide to go for the controlled detonation.

"Our priority is to keep the area safe," the spokesperson said, though since Friday, when the suspected attacker confessed that he had explosives stored at home, all the buildings around Holmes's apartment have been evacuated.

Police said that the controlled detonation could be accompanied by loud noises, a big explosion and fire.

Up to now the videos taken have surprised police and federal agents by the sophistication and complexity of the devices inside, but ruled out that they could be connected to timers to go off at a certain time.

In the suspect's small apartment agents have found what appear to be some 30 mortars and large-caliber bullets, which they will first try to deactivate and take to a secure place. EFE