Twelve people were killed and 59 others injured at a Batman movie premier, where a lone, heavily armed gunman burst into a packed theater in a suburb 10 miles east of Denver during the wee hours of Friday.

President Barack Obama addressed the nation at a Friday morning press conference, calling the act "mindless, evil, senseless" and asked the nation to bond together in this moment of crisis.

Local police identified the perpetrator to be James Holmes, 24, who was detained in the parking lot of the Century 16 Movie Theaters in Aurora shortly after the shooting spree. Police also found two handguns, a rifle, a shotgun and a gas mask in the vehicle of Holmes, according to Aurora Police Chief Dan Oates.

Oates said Holmes was wearing black riot gear at the time of his arrest, similar to the costuming of a villain in the Batman movie "The Dark Knight Rises."

A University of Colorado medical center spokesperson confirmed that Holmes was a Ph.D. student in the neuroscience program at the university, but dropped out in June.

According to the police sources, Holmes is a San Diego native, whose parents issued a statement through San Diego Police giving condolences to families involved in the shooting.

Eyewitness said the gunman burst through a side door of the packed theater at 12:30 a.m. local time Friday and threw canisters of a "hissing" gas into the crowd before opening fire, trapping theatergoers in their seats. "They never had a chance," one witness said.

Police chief Oates also said the suspect's apartment, filled with University of Colorado Medical School students at nearby 17th and Peoria Streets, had been "booby trapped in a sophisticated way." At least five neighboring apartment buildings were evacuated as police used remote cameras in an attempt to see things inside Holmes' apartment.

Holmes is not believed to be connected to any anti-government or paramilitary groups inside the United States.