A large crowd, some hugging and crying, attended a vigil near the entrance to the theater's parking lot at the site of a makeshift memorial.
Some people left candles, others stuffed animals. Children could be seen holding American flags as mourners sang songs. A sign read, "7/20. Gone Not Forgotten."
The vigil came hours after authorities removed all hazards from the home of the suspected gunman, James Holmes. After carefully navigating a pervasive booby trap his apartment, residents evacuated from four surrounding apartment buildings were allowed back in their homes.
The only building that remains evacuated is Holmes' building at 1690 Paris Street, the Aurora Police Department announced on Twitter. The FBI Evidence Response Team remained on scene to gather evidence from the apartment, which was expected to take several hours.
The 24-year-old Holmes lived in a third-floor unit in the apartment complex.Multiple detonations were required to clear the apartment of any serious hazards. Authorities say the booby traps were set up to kill whoever walked through the door. According to FBI Special Agent Jay Racone, the unsuspecting person would have "sustained significant injuries and/or lost their lives."
See an outline of events and facts surrounding the Colorado theater shooting
"Who was most likely to enter that location after he planned and executed this horrific crime? It was going to be a police officer. So make no mistake about it, what was going on there, and if you think we're angry, we sure as hell are," said Aurora Police Chief Dan Oates at a Saturday afternoon press conference.
Around midnight the night of the shooting, Holmes had techno music set up to start blaring, even though he wasn't there. The woman who lives in the apartment underneath him went up stairs to complain, realized his door was unlocked and almost walked in. The fact she didn't may have saved her life.
The hazards removed from Holmes' apartment have been removed and transported to a disposal site. FBI agents discovered that the apartment was booby-trapped by using a camera at the end of a 12-foot pole to look inside.
Deputy Aurora Fire Chief Chris Henderson called the booby trap "extensive." Photos of Holmes' apartment appeared to also show jars full of ammunition and liquid, reported to be accelerant. Oates said he had never seen anything like it.
Read more information about shooting suspect James Holmes
Police evacuated the building, which is about 4 miles from the theater, and surrounding residences after arresting Holmes, who is the suspect behind a mass shooting Friday at a midnight screening of "The Dark Knight Rises."
Police say a gunman barged into a packed auditorium at the Century 16 Movie Theaters at the Aurora Town Center, set off gas canisters and began shooting into the crowd - picking off people who tried to flee. Twelve people were killed and 58 were injured, with 30 remaining hospitalized and 11 in critical condition.
As of now, it appears Holmes could face state prosecution in the shooting, Oates said. Holmes remains in solitary confinement and will make his first court appearance at 9:30 a.m. Monday. Holmes will reportedly be represented by James O'Connor, the area's head public defender.
Authorities said Holmes acted in a premeditated manner. He collected 6,000 rounds of ammunition in the 60 days before the shooting.
Read statements from public officials about the Colorado theater shooting
Saturday afternoon, the Arapahoe coroner released a confirmed list of the 12 fatalities in the theater shooting, which is said to be the worst mass shooting in modern U.S. history. Among those dead were a 27-year-old Navy Sailor, a 29-year-old Air Force Reservist and a 6-year-old girl.
Meanwhile, the community of Aurora gathered together for a vigil Saturday night. An official vigil was scheduled for Sunday at 6:30 p.m. MT. President Barack Obama will also visit Colorado on Sunday to visit victims and their families. It was not known if he would speak at the vigil.
View photos from the scene of the shooting at an Aurora, Colorado theater
