The man who allegedly shot seven people dead and injured three more at a university in Oakland was targeting a female school official, police say.
One L Goh began shooting randomly when he discovered the administrator was not there, Oakland Police Chief Howard Jordan said on Tuesday morning.
The shooting took place on Monday at Oikos University.
The suspect, a 43-year-old former student at the college, surrendered at a supermarket in nearby Alameda city.
The suspect arrived at the university with the "the intent of locating an administrator. He then went through the entire building systematically and randomly shooting people," Mr Jordan told ABC News' Good Morning America.
"We've learned that the suspect was upset with the administration at the school. He was also upset that students in the past, when he attended the school, mistreated him, disrespected him, and things of that nature.
"He was having, we believe, some behavioural problems at the school and was asked to leave several months ago."
Mr Jordan described the suspect as a "chaotic, calculated and determined gentleman", adding that it was the gunman's intention to kill people.