Police are moving cautiously as they prepare an attempt today to enter the booby-trapped apartment of the suspect in the Aurora, Colo., theater massacre that killed 12 people and injured 58.
Firefighters are monitoring the apartment building for gases in an effort to determine what chemicals they say 24-year-old James Holmes might have used to booby-trap the place -- in case the materials go off.
Police evacuated the building and surrounding residences after arresting Holmes as the suspect in a mass shooting Friday at a midnight screening of "The Dark Knight Rises."
FBI agents and police discovered it was booby-trapped when they used a camera at the end of a 12-foot pole to look inside.
Photos of Holmes' apartment appeared to show trip wires, jars full of ammunition and liquid and other items unlike. Aurora's police chief says he's never seen anything like it.