Bomb Squads Disarm Traps At Holmes’ Apt [VIDEO]

Police say the Colorado shooting suspect planned the rampage that killed 12 and injured dozens of others at a suburban movie theater with "calculation and deliberation."

They say James Holmes received months of deliveries in advance that authorities believe armed him for battle and were used to rig his apartment with explosives aimed at killing first responders.

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Aurora Police Chief Dan Oates says "You think we're angry? We sure as hell are angry."

Authorities are still working to clear dangerous explosive materials from inside Holmes' suburban Denver apartment, which Oates says was booby trapped to kill "whoever entered it," noting it would have likely been one of his officers.

A law enforcement official says federal authorities have detonated one small explosive and disarmed another.

The official says Holmes' apartment appears to have three types of explosives -- jars filled with accelerants, chemicals that would explode when mixed together and more than 30 "improvised grenades."

FBI Special agent James Yacone says that while most of the explosives have been rendered safe, "the threat has not been completely eliminated." But he says families should be allowed back into their apartments by Sunday.

The Associated Press contributed to this story.