OAKLAND, Calif. - Ahmad Sayeed was sitting in his class at tiny Oikos University when a gunman burst into the lecture hall and held a terrified school receptionist hostage.

Within moments, the gunman identified by authorities as South Korean immigrant One Goh began randomly firing at students, killing seven and wounding three in Monday's violence.

"Everyone was scared, panicked," said Sayeed on Wednesday as he sat at home in California, nursing a shoulder wound. "He's shooting and we are all screaming. He just started shooting at everyone."

The 36-year-old, who immigrated from Afghanistan three years ago, said he at first did not understand what the gunman was saying, but he saw the look of terror on the face of the school receptionist, Katleen Ping, 24. And he saw the gun pointed at her.

"He brought her in there with the gun and she looks very scared," Sayeed said.

Ping, one of the seven people killed Monday, worked at the front desk in the university's administration department.

Meanwhile, an administrator at the university said Wednesday she believed she was the alleged gunman's primary target after she rejected his repeated requests for a refund of his tuition.

But Ellen Cervellon, director of the nursing program, said she wasn't on campus when her former student came looking for her, then went on his rampage.

In an interview with The Associated Press, a shaken Cervellon said the killings are haunting her.

"I have that weight on my shoulders and I don't know what to do with it," she said, her voice quavering. "Every single one of those students were going to be an excellent, excellent nurse. They're in my heart, and they always will be."

Goh, 43, was charged Wednesday with seven counts of murder and three counts of attempted murder, plus a special circumstance allegation of committing multiple murders that could make him eligible for the death penalty.

Shackled and showing little emotion, Goh said nothing during a brief court appearance other than a soft "yes" when the judge asked if he understood the charges. He did not enter a plea.

In a police affidavit, Officer Robert Trevino said Goh acknowledged going to Oikos on Monday with a .45-calibre handgun and four magazines of ammunition.

"He admitted to kidnapping a woman and forcing her from her office into a classroom at gunpoint," Trevino said in the statement. "He admitted to shooting and killing several people inside the classroom, before taking one of the victim's car keys and fleeing the scene in the victim's car."

Police arrested Goh about an hour after the shooting spree at a supermarket a few miles (kilometres) from campus.

Cervellon said Goh dropped out of the nursing program at the tiny private school around November but returned numerous times to ask her for a full tuition refund. Goh got angry when she told him the school could not refund all his money because he had been enrolled for nearly half of the program, she said.

Police initially said Goh was expelled, although Cervellon said that he was not.

Cervellon said Goh had previously said that classmates were picking on him at the school, which was founded to help Korean immigrants adjust to life in America. Goh is a native of South Korea who became a U.S. citizen.

Oakland Police Chief Howard Jordan has said Goh was upset because other students had teased him about his poor English skills.

However, Cervellon and nursing professor Romie John Delariman said they never heard about or witnessed Goh being ridiculed for problems with English. Delariman said Goh was a good student who didn't seem to struggle with his second language.

"He was a full-time student and was really motivated. If I taught something, he would be the first person in line to do it," Delariman said.

Goh appeared to be the aggressor in exchanges with others at the school, according to Efanye Chibuko, whose wife, Doris Chibuko, was among those killed.

Chibuko said his wife, a native of Nigeria who was elected president of her nursing class, felt Goh was unstable.

"My wife was afraid of him," he told the AP. "She was afraid he would do something like he did. She knew the other victims, and they talked about it. They were afraid that he was going to come back and do what he did."

Chibuko said he's angry with school officials for not doing more to protect the students.

"They were all living in fear. My wife told me the guy had been violent toward the school staff and had kicked the walls and stuff like that," he said. "So they knew. They should have had security in place."

Delariman said he noticed that Goh had problems, in particular, dealing with women in his predominantly female nursing classes.

"He can't stand women," Delariman said. "He said he never used to work with women, or deal with women in a work setting or a school setting."