A day after the shooting, which claimed 12 lives and left 58 people injured, it remained unclear what was the motive of the gunman, identified as 24-year-old James Holmes, to fire indiscriminately at the moviegoers during the premiere of the latest Batman film 'The Dark Knight Rises' in Aurora, a suburb of Denver, Colorado.
As police began the process of notifying the families of those killed, authorities grappled with how to collect possible evidence from Holmes' apartment that was allegedly booby-trapped by him before leaving for the theatre.
Police evacuated hundreds of residents from five apartment buildings, including the one where Holmes lived, after he told them he had rigged his one-bedroom apartment with explosives.
"It is a very vexing problem how to enter that apartment safely. I personally have never seen anything like what the pictures show us is in there," city police chief Dan Oates was quoted by CNN as saying.
Technicians made a first attempt yesterday to disarm the traps, believed to include explosives, but withdrew when it became clear the property was too dangerous to enter. Federal government experts are due to arrive today for a second attempt.
"Investigators will use a robot to disarm trip wires linked to explosives, and then use that same robot to remotely remove the improvised explosive devices," a law enforcement official with direct knowledge of the operation told CNN.
Firefighters were monitoring the block of flats for gases in an effort to identify what chemicals might have been used in the booby-traps.
Describing the shooting as an "evil" act which was "beyond reason," President Obama today said his government "stands ready to do everything necessary to bring whoever's responsible for this heinous crime to justice."
A vigil was organised to mourn the death of innocent victims as hundreds held candles, many sobbing and hugging each other in an outpouring of grief.
