12 killed, 58 wounded in Colorado theater shooting (+video)

"As you can understand, the Holmes family is very upset about all of this," Lt. Andra Brown, the San Diego police spokeswoman, told reporters in the driveway of the family home. "It's a tragic event and it's taken everyone by surprise. They are definitely trying to work through this."

Police released a statement from his family that said: "Our hearts go out to those who were involved in this tragedy and to the families and friends of those involved."

There have been no indications so far that Holmes had any run-ins with the law before Friday.

Tom Mai, a retired electrical engineer, said Holmes was a "shy guy" who came from a "very, very nice family."

Holmes graduated from University of California, Riverside, in the spring of 2010 a bachelor's degree in neuroscience, a school spokesman said. Mai said the mother told him Holmes couldn't find a job after earning a master's degree and returned to school.

He enrolled in the Ph.D. neuroscience program at the University of Colorado-Denver in June 2011 but left the program last month, according to the university.

Holmes lived in an apartment in Aurora, and FBI agents and police who went there discovered it was booby-trapped when they used a camera at the end of a 12-foot pole to look inside. Authorities evacuated surrounding residences, and about two dozen people headed to a shelter set up by the Red Cross at a local school.

Police were not able to enter the apartment Friday night and Oates said they will again on Saturday.

"It is a very vexing problem how to enter that apartment safely," he said.

Associated Press writers Kristen Wyatt, Steven K. Paulson, Ivan Moreno and Mead Gruver in Aurora, Dan Elliott and Colleen Slevin in Denver, Tom Hays in New York, Monika Mathur and Jennifer Farrar at News Research Center and Alicia A. Caldwell and Eileen Sullivan in Washington contributed to this report.