The man suspected of shooting seven people dead and injuring three more at a university in Oakland had been teased over his poor English, police say.

One L Goh, 43, felt "disrespected" and "isolated", and was expelled from the school for behavioural problems, Police Chief Howard Jordan said on Tuesday.

He was allegedly looking for a female official when the shooting took place on Monday at Oikos University.

The former student surrendered at a supermarket in nearby Alameda city.

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

The police chief added that Mr Goh dragged the university secretary into a classroom, told people to line up, and began shooting when some people did not co-operate.

'Chaotic, calculated'

The suspect arrived at the university at about 10:30 (17:30 GMT) on Monday 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 on Tuesday.

"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.

US campus shootings February 2010:A professor at the University of Alabama at Huntsville, Amy Bishop, opens fire at a faculty meeting, killing three colleagues and wounding three others February 2008: Former graduate student Steven Kazmierczak kills five students, wounds 16 at Northern Illinois University and kills himself April 2007: Seung-Hui Cho kills more than 30 people in a dorm and a classroom at Virginia Tech, before turning the gun on himself April1999:Two students kill 12 others and a teacher and wound more than 20 before killing themselves at Columbine High School

"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.

Five people died at the scene, and two died later at the hospital. Three wounded victims have been released from hospital.

According to the police chief, the victims ranged in age from 21 to 40.

Among the dead were six women and one man,the San Francisco Chronicle reports. Some are believed to have been foreigners - from Korea, Nigeria, Nepal and the Philippines. Officials have not released the names of the victims.

Local media have described the gunman as an American man of Korean origin, who does not have a criminal record.

Mr Goh has some outstanding debts and minor traffic offences in Virginia, where he used to live.

He appears to have been planning the attack for weeks, police say.

He is currently being held without bail on suspicion of murder, attempted murder, kidnapping and carjacking, and is expected to be formally charged in court on Wednesday, according to the San Francisco Chronicle.

Police say they are still looking for the weapon used during the attack, using a robot to search a nearby estuary. Mr Jordan has described it as a semi-automatic handgun that was purchased legally.

A memorial service is scheduled for 18:00 local time on Tuesday evening.

The attack comes after an Ohio high school student opened fire on fellow students in February, killing three and injuring six.