Oakland police said a 43-year-old former student named One L. Goh walked into Oikos University Monday morning and began a rampage that left seven people dead and three people wounded, while others fled for their lives.
It was an "extremely chaotic scene," police Chief Howard Jordan said.
Soon after the shooting, heavily armed officers swarmed the tiny college of fewer than 100 students. For a time, police believed the gunman could still be inside. But he wasn't.
Instead, officers said he apparently drove from campus before surrendering to officers inside a supermarket.
"It's going to take us a few days to put the pieces together," Jordan said.
Jordan told "Good Morning America" on Tuesday that the suspect was "upset with the administration of the school" and that the suspect had been "mistreated" and "disrespected" by students.
Those connected to the school, including the founder and several students, described the gunman as a former nursing student. The chief said Goh is a South Korean national who's a former student of the university.
Police first received an emergency call at 10:33 a.m. reporting a woman on the ground bleeding. As more calls came in from the school, the first arriving officer found a victim suffering from a life-threatening gunshot wound, he said.
"Potential victims remained inside the building either trapped by a locked door which officers were unable to open," Jordan said. Others were unable to flee because they were injured, he said.
Jordan said about 35 people were in or near the building when gunfire broke out. Of the seven deaths, five died at the scene and another two at the hospital. The wounded victims are in stable condition, and at least one person has been released from the hospital. He told "Good Morning America" on Tuesday the victims ranged in age from 21 to 40.
"This unprecedented tragedy was shocking and senseless," Jordan said.
Art Richards said he was driving by the university on his way to pick up a friend when he spotted a woman hiding in the bushes. He pulled over, and when he approached her, she said, "I'm shot" and showed him her arm.
"She had a piece of her arm hanging out," Richards said.
As police arrived, Richards said he heard 10 gunshots coming from inside the building. The female victim told him that she saw the gunman shoot one person point-blank in the chest and one in the head.
Tashi Wangchuk, whose wife attended the school and witnessed the shooting, said he was told by police that the gunman first shot a woman at the front desk, then continued shooting randomly in classrooms.
Wangchuk said his wife, Dechen Wangzom, was in her vocational nursing class when she heard gunshots. She locked the door and turned off the lights.
The gunman "banged on the door several times and started shooting outside and left," he said. Wangchuk said no one was hurt inside, but the gunman shot out the glass in the door. He said she did not know the man.
Television footage showed bloodied victims on stretchers being loaded into ambulances. Several bodies covered in sheets were laid out on a patch of grass at the school. One body could be seen being loaded into a van.
Myung Soon Ma, the school's secretary, said she could not provide any details about what happened at the private school, which serves the Korean community with courses from theology to Asian medicine.
"I feel really sad, so I cannot talk right now," she said.
The 19-year-old U.S. Army Reservist told her family that that the gunman was a student in her nursing class who had been absent for months before returning Monday. The gunman entered the classroom and ordered students to line up against the wall.
When he showed his gun, students began running and he opened fire, her family said.
"She told me that a guy went crazy and she got shot," brother Paul Singh told the newspaper. "She was running. She was crying; she was bleeding, it was wrong."
Pastor Jong Kim, who founded the school about 10 years ago, told the newspaper that he did not know if the shooter was expelled or dropped out. Kim said he heard about 30 rapid-fire gunshots in the building.
"I stayed in my office," he said.
Deborah Lee, who was in an English language class, said she heard five to six gunshots at first. "The teacher said, 'Run,' and we run," she said. "I was OK, because I know God protects me. I'm not afraid of him."
The suspect was detained at a Safeway supermarket about an hour after the shooting.
A security guard at the supermarket approached the man because he was acting suspiciously, KGO-TV reported. The man told the guard that he needed to talk to police because he shot people, and the guard called authorities.
"He didn't look like he had a sign of relief on him. He didn't look like he had much of any emotion on his face," said Lisa Resler, who was buying fruit at Safeway with her 4-year-old daughter when she saw the man.
Goh also called his father soon after the shooting and told him what happened, the police chief said. The father also called authorities, Jordan said.
The suspect's brother was killed in a car accident last year in Virginia while on active duty in the U.S. Army, according to Stars and Stripes newspaper. The suspect attended the funeral of Sgt. Su Wan Ko in Centreville, Virginia, after the March 8, 2011, accident.