A former student at a small Christian university had gone to the building to find a female administrator and opened fire when she was not there, killing at least seven people, police said Tuesday.
One L. Goh "then went through the entire building systematically and randomly shooting victims," Oakland Police Chief Howard Jordan said at a news conference.
"We do know that he was upset at administrators at the school. We do know that he was upset with several students here because of the way he was treated when he was enrolled here two months ago," Jordan said.
He said Goh had been teased although he did not elaborate. The 43-year-old South Korean national had been expelled, possibly for behavioral problems, according to Jordan.
"We've learned that this was a very chaotic, calculated and determined gentleman that came there with a very specific intent to kill people, and that's what his motive was and that's what he carried out," Jordan told "Good Morning America."