* Six-year-old girl among the 12 killed
* Governor calls killer "diabolical"
* Says no clues as to possible motive (Adds details)
By Mary Slosson and Chris Francescani
AURORA, Co., July 22 (Reuters) - Residents of a Denver suburb mourned their dead on Sunday from a shooting rampage by a "demonic" gunman who killed 12 people and wounded 58 after opening fire at a cinema showing the new Batman movie.
President Barack Obama headed to Aurora, Colorado, on Sunday to meet families grieving their losses Friday's mass shooting that has stunned the nation and rekindled debate about guns and violence in America.
Churchgoers dabbed at their eyes as special prayers were offered in Aurora for those who died in the town of 325,000, which is not far from the scene of the 1999 Columbine High School student massacre.
"Our culture needs to change," Father Mauricio Bermudez told a packed mass at the Queen of Peace Catholic Church in Aurora.
"What kind of people are we becoming? Today, we must change. Today is the day."
The victims, who ranged in age from a girl of six to a man of 51, died early on Friday when a gunman police identified as graduate-school dropout James Holmes opened fire at a packed midnight premiere of the Batman film, "Dark Knight Rises."
"We're still reeling," Aurora Mayor Steve Hogan said at a memorial late on Saturday for one young shooting victim.
A vigil was scheduled for 6:30 p.m. on Sunday in front of Aurora City Hall organized by civic community and religious leaders.
Obama's trip comes as investigators are deepening a probe into Holmes. He was arrested at the multiplex immediately after the shootings and local and federal authorities disarmed explosives in his booby-trapped apartment on Saturday.
Aurora Police Chief Dan Oates said the shooting followed months of "calculation and deliberation," as Holmes received a "high volume" of deliveries of weaponry to his work and home.
Colorado Governor John Hickenlooper, speaking on NBC television's "Meet the Press" program, said there were still no clues as to the motive for the shooting. But he said Holmes was "a twisted, really delusional individual" who had not been cooperating with authorities.
"He was diabolical, demonic," Hickenlooper said.
"I think of him almost as a terrorist. He wanted to take away, not just from the people here but from the country, our ability to enjoy life," he said.
On Saturday afternoon, the local coroner's officer released the names of the 12 people killed, including those of the six-year-old girl, a young man celebrating his 27th birthday and an aspiring sportscaster who had barely escaped a shooting in a Toronto mall earlier this summer.
Those who witnessed the shooting told of a nightmarish scene, with dazed victims bleeding from bullet wounds, spitting up blood and crying for help.
For many, it evoked memories of the 1999 massacre at Columbine High School in Littleton, 17 miles (27 km) from Aurora, where two students opened fire and killed 12 students and a teacher.
The incident has also reverberated in the U.S. presidential race. Both Obama and his Republican rival, Mitt Romney, toned down their campaigns on Friday, pulled ads from Colorado and dedicated scheduled events to the victims.
In Rome on Sunday, Pope Benedict expressed dismay and sadness at the shooting.
"I was deeply shocked by the senseless violence which took place in Aurora, Denver," he said in his regular Sunday Angelus address.
"I share the distress of the families and friends of the victims and the injured, especially the children," he said.
Holmes was arrested in a parking lot behind the cinema. He was armed with a Smith & Wesson M&P .223 semi-automatic rifle, similar to an AR-15 assault rifle, a 12-gauge shotgun and a Glock .40-caliber handgun. Police found an additional Glock .40-caliber handgun in his car. All the weapons were legally bought in the previous 60 days.
Authorities said Holmes had dyed his hair red and called himself "the Joker" in a reference to Batman's comic-book nemesis, was due to make an initial court appearance on Monday.
Sources familiar with the investigation said some 30 softball-sized containers filled with gunpowder were found in Holmes' apartment, together with containers filled with "incendiary liquids" intended to fuel a fire from the initial explosions, as well as bullets meant to ricochet around the apartment.
Holmes was being held in solitary confinement to protect him from other prisoners, a routine move in high-profile cases, said Grayson Robinson, sheriff of Arapahoe County.
He is due to make his initial appearance before a judge at the Arapahoe County Justice Center on Monday morning.
Little has surfaced from his past to suggest he was capable of such violence.
Until last month, Holmes was studying for a doctoral degree in neuroscience at the University of Colorado's Anschutz Medical School, a few blocks from his apartment.
The University of Colorado Hospital, which treated some of the shooting victims, said 10 people had been released and five remained in critical condition. The Medical Center of Aurora said four of its seven patients remained in intensive care, while three others were on the main trauma floor.
A memorial of flowers, candles and stuffed animals has sprung up where the shootings took place. A handwritten sign read: "7/20 gone not forgotten." (Additional reporting by Stephanie Simon, Keith Coffman, Edith Honan, Dan Whitcomb and Donna Smith in the United States and James Mackenzie in Rome; Editing by Tom Brown and David Brunnstrom)