OAKLAND, Calif. - A nursing student expelled from a small Christian university and upset about being teased over his poor English skills opened fire at the school, going from room to room in a rampage that left six students and a secretary dead, police said Tuesday.

One L. Goh, 43, forced the secretary into a classroom at Oikos University in Oakland on Monday, told people to line up and, when some didn't co-operate, began his shooting spree, police Chief Howard Jordan said.

"It's very, very sad," Jordan said. "We have seven people who didn't deserve to die and three others wounded because (of) someone who couldn't deal with the pressures of life."

Goh, a South Korea native who became a U.S. citizen, was expelled in January for behavioural problems from the small private school of fewer than 100 students, Jordan said. The chief said Goh had anger management issues with other students.

Jordan said Goh appeared to have been planning the attack for several weeks.

Goh was upset with administrators and several students at the college, which an official said offered classes in Korean and English and was founded to help Korean immigrants adjust to a new country and find careers in nursing and ministry.

"They disrespected him, laughed at him," Jordan said. "They made fun of his lack of English speaking skills. It made him feel isolated compared to the other students."

Jordan said Goh tried to find a female administrator Monday and began shooting when he learned she wasn't there. The victims, who range in age from 21 to 40, were from various countries, including Nigeria, Nepal and the Philippines.

Goh was being held without bail Tuesday after being booked on suspicion of murder, attempted murder, kidnapping and carjacking, according to sheriff's Sgt. J.D. Nelson, who said the suspect likely would make his first court appearance Wednesday.

Police were still looking for the gun used, which Jordan described as a semiautomatic handgun that was purchased legally.

Goh has no criminal history, but he has debts and minor traffic citations in his former home state of Virginia and was evicted from one apartment complex.

His brother, a soldier on active duty, was killed in a car crash last year in Virginia, according to Stars and Stripes newspaper.

The three surviving shooting victims were all released from Highland Hospital by Monday night, according to hospital officials, who would not release details on the nature of the injuries treated.

Goh fled from the school in a Honda Accord that belonged to one of the victims, Jordan said. The suspect was detained at a supermarket nearby, about an hour after the shooting.

Authorities have not released the names of the victims.

School secretary Katleen Ping is believed to be among the first victims of the shooting, according to her family.

Ping's father, Liberty Ping, said she had been working at Oikos for less than a year and had come to the U.S. from the Philippines in 2007. He described her as the rock of the family who leaves behind a 4-year-old son.

"We're just focusing on the positives," Liberty Ping said. "She's with the Lord. She's in a better place right now."