US President Barack Obama has paid an emotional tribute to the victims and survivors of the Colorado cinema massacre, as the shaken US town of Aurora held a tearful vigil for the 12 dead filmgoers.
Obama, making a visit to the stricken Colorado town, said he shed tears with relatives of those who died as the community struggles to recover from the shooting at a screening of the latest Batman movie, which also left 58 injured.
"I confessed to them that words are always inadequate in these types of situations," he said as thousands gathered for a vigil outside the municipal centre in Aurora.
Speaking after visiting with families in hospital, he said he "had the chance to give folks some hugs, and to shed some tears, but also to share some laughs" as families remembered the "wonderful" lives of their loved ones.
The alleged gunman, 24-year-old James Holmes, is accused of bursting into a packed midnight screening of The Dark Knight Rises, throwing two canisters of noxious gas into the crowd, and then shooting at random.
The victims included a six-year-old girl, Veronica Moser-Sullivan, whose mother was also critically wounded.
Shortly after Obama's speech, thousands of locals offered loud rounds of spontaneous applause as police officers, army and other officials came towards a stage for the start of the vigil.
"While our hearts are broken, our community is not," Aurora Mayor Steve Hogan told the crowds, which included many people in tears.
Colorado Governor John Hickenlooper drew applause when he refused to mention Holmes by name, referring to him only as "suspect A" and insisting that the priority should be to remember the 12 victims.
He then read out their names, after which the crowd said, "We will remember".
Police revealed on Sunday that they had found Holmes's computer inside his booby-trapped apartment, which could provide crucial details about how he planned and executed the attack, reportedly over a number of months.
Holmes, who is due to make his first court appearance on Monday (local time), is being held in solitary confinement for his own protection, a police spokeswoman said.
It was also reported that Holmes had applied to join a private gun club a few weeks before the shooting, but his paperwork appeared suspicious and he was not approved.
Calls for another look at America's gun laws are mounting in the aftermath of the tragedy as it emerged that the suspect bought his four weapons legally, as well as thousands of rounds of ammunition on the internet.
Aurora is located just 32km from the scene of the 1999 Columbine High School massacre, in which two students shot dead 13 people before committing suicide.
City police chief Dan Oates praised his men for spotting Holmes as a suspect in the "chaos" that followed the shooting, as officers could have mistaken him for an arriving SWAT officer, because of his full body armour.
Actress Anne Hathaway became the latest cast member to voice her shock at the killings, after Warner Brothers, the studio behind the new Batman movie, said it was withholding box office data out of respect for the victims.
"My heart aches and breaks for the lives taken and altered by this unfathomably senseless act. I am at a loss for words how to express my sorrow," said Hathaway, who plays Catwoman.