The president of the University of California system called the deadly rampage in the seaside college town of Isla Vista near UC Santa Barbara "almost the kind of event that's impossible to prevent and impossible to predict."
Janet Napolitano, former secretary of Homeland Security and UC president, spoke after a commencement speech in Oakland on May 24, one day after the killing spree that left seven people including the gunman dead and 13 others injured.
- Rampage in Isla Vista: Victims, Photos, Timeline
The mass shooting in the UC Santa Barbara community is "almost the kind of event that's impossible to prevent and impossible to predict," Napolitano said. She also issued a statement that said she was "shocked and deeply saddened" by the shooting and sending thoughts and prayers "to the victims of this tragedy, their families and the entire Santa Barbara community."
Six UCSB students were were killed by 22-year-old Elliot Rodger, according to authorities. The Santa Barbara City College detailed his plans to go on a murderous rampage in a written manifesto and YouTube videos posted shortly before Friday night's violence.
Rodger stabbed three men to death inside his Isla Vista apartment before fatally shooting three others in the community, officials said. Thirteen other victims suffered gunshot wounds or were injured when Rodger struck them with his BMW 3 series coupe, officials said. Three remained hospitalized Monday.
The gunman died of a self-inflicted gunshot wound to the head after a shootout with deputies, according to the sheriff's department. A family friend confirmed to NBC News Sunday that Rodger's parents rushed to Isla Vista as the killings began after discovering the troubling manifesto that outlined plans for what Rodger called "retribution."
After the shootout and a crash that brought an end to the violence, deputies found three semi-automatic handguns along with 400 unspent rounds in the car. All were purchased legally.
Rodger's family has disclosed their son was under the care of therapists.
"He convinced them that it was all a misunderstanding," Sheriff Bill Brown said.
Though Rodger told deputies that he was having social problems and was likely going to leave school, "he was able to convince them that he was not a threat to himself or to anyone else at the time."
The killings renewed the discussion as to how well Southern California law enforcement officials are trained to deal with people who have mental health issues.
The Associated Press contributed to this report.