Questions, but few answers, in Colorado shooting; 12 dead, dozens hurt Officials carefully searched the Colorado home of the suspect in the nation's deadliest mass shooting in more than five years, a rampage by a lone gunman that turned the local premiere of the last chapter of the Batman trilogy into the latest national tragedy on Friday. According to local officials, at least 12 people were dead and dozens were injured in the shooting by the gunman, who wore body armor and a gas mask when he entered the movie theater in suburban Aurora, Colo., after midnight Friday. He then set off at least one canister of gas and opened fire with a variety of weapons. The attack came about half an hour into the showing of "The Dark Knight Rises," an eagerly awaited summer epic that had fans lining up for hours and scalpers reportedly selling tickets for as much as $300. The suspect was identified as James Holmes, 24, whose apartment on Paris Street in Aurora was being searched by officials. Aurora Police Chief Dan Oates said the apartment was booby-trapped with explosives, forcing authorities to evacuate five buildings along the street as a precaution. PHOTOS: 'Dark Knight Rises' shooting Little was immediately known about Holmes or about a motive. He was described by law enforcement sources as a loner. He was a student at the University of Colorado Denver/Anschutz Medical Campus but the school said he was in the process of withdrawing from the graduate program in neuroscience. He was a 2006 graduate of Westview High School in San Diego. Holmes is expected to appear in court on Monday at the Arapahoe County Justice Center in Centennial, south of Denver. No formal charges have been filed, said John Sarche, a spokesman for the Colorado Judicial Branch. Holmes" family lives in the San Diego area but played no role in the shootings, San Diego police spokeswoman Andra Brown told reporters at the family house. At a televised news conference, she read a statement from the family: "Our hearts go out to those who were involved in this tragedy and to the families and friends of those involved." Police said the family was asking the media to respect their privacy. President Obama, who cut short a campaign swing through Florida, led the nation in mourning and prayer. "It reminds us of all the ways that we are united as one American family," he said. But the remorse was tinged with the need to once again try to explain a senseless act -- the worst mass shooting since the Virginia Tech tragedy in 2007. Thirty-two people, plus the shooter, died in that massacre. Friday's attack also brought back memories of Colorado's other mass shooting, in 1999 at Columbine High School; that shooting left 12 students and one teacher dead, plus the two shooters. Now, even as we learn how this happened and who's responsible, we may never understand what leads anybody to terrorize their fellow human beings like this. Such violence, such evil is senseless. It's beyond reason," Obama said. "This is not only an act of extreme violence, it is also an act of depravity," Colorado Gov. John Hickenlooper said in a prepared statement. It is beyond the power of words to fully express our sorrow this morning. Our prayers and condolences go first to the families of those killed, and we share the grief of everyone affected by this senseless event. Much of the nation awoke on Friday morning to reports of the shootings in Aurora; the first reports were often as chaotic as the events in the theater. The toll of casualties rose then fell as officials scrambled to give first aid and transport the wounded to hospitals. According to police and witnesses, most of the audience didn't take the gunman seriously when he entered the movie house through an exit door. He appeared to be in costume, wearing body armor and a gas mask, but others too had donned special attire for the movie about a superhero known as the Caped Crusader. Some witnesses told reporters that they thought he was part of a publicity stunt or prank. I thought it was showmanship. I didn't think it was real," one witness said. But that quickly ended as the gas canister went off and the steady pop, pop, popping noise went on, witnesses said. The gas smelled like pepper. There were bullet [casings] just falling on my head. They were burning my forehead," Jennifer Seeger told reporters, an account that was repeated by other witnesses. "Every few seconds it was just boom, boom, boom," Seeger said. He would reload and shoot and anyone who would try to leave would just get killed. Ten bodies were recovered from the theater. At least two people died en route to hospitals.