Investigators looking for clues to the motive behind a shooting rampage at a screening of the new Batman movie are seeking to enter the suspect's elaborately booby-trapped apartment.
As the suburb of Aurora in Denver, Colorado, grieves, police warned that removing trip wires could detonate the explosives.
The FBI and Homeland Security Department said there was no information to indicate that more shooting sprees were planned at cinemas around the US, according to an intelligence bulletin.
Twelve people were killed and 58 others injured in Friday's attack. A few of those suffered injuries not from shots but in the chaos that ensued as the audience tried to flee the smoke-filled theatre in a panicked dash for the doors, authorities said. Among the wounded, 11 were said to be in a critical condition.
It remains unclear what drove the suspect, identified as James Holmes, 24, to fire round after round at the unsuspecting audience watching The Dark Knight Rises.
After the shooting, police said they found that Holmes's nearby apartment had been booby-trapped and ordered residents in the building and surrounding homes to evacuate.
Authorities were not able to enter the apartment on Friday night. Scores of law enforcement officials, including local bomb squad technicians and dozens of federal Bureau of Alcohol, Tobacco, Firearms and Explosives agents gathered again at the apartment on Saturday morning.
"It's safe right now with the evacuations so we don't want to rush anything," said Aurora Police Sergeant Cassidee Carlson.
The apartment contains jars of unknown accelerants and trip wires, she said, noting that authorities may be forced to detonate the explosives. Fire crews stood by ready to fight any ensuing blaze.
Police grimly went door to door late on Friday with a list of victims killed in the worst mass shooting in the US in recent years, notifying families who had held out hope that their loved ones had been spared.