Colorado police probing the deadly mass shooting at a movie theater outside Denver say bomb experts have eliminated all major explosives at the shooter's booby-trapped apartment.

Aurora Police Chief Dan Oates told reporters Saturday afternoon that the apartment was rigged to kill whomever entered it first. He said in all likelihood that would have been a police officer.

Twelve people were killed and dozens wounded early Friday as a gunman, identified as 24-year-old student James Holmes, sprayed scores of bullets into a crowded theater.

The White House says President Barack Obama will go to Colorado Sunday to meet with families of the victims and local officials.

The heavily-armed Holmes was arrested just outside the theater immediately after the bloodbath, in possession of a rifle, a shotgun, two handguns, a gas mask and a bulletproof vest. He is being held in solitary confinement.