ISLA VISTA, California - The first time Sheriff's deputies were called to the apartment of Elliot O. Rodger, the dispute seemed minor, almost laughable.

Rodger had accused a roommate, Chen Yuan Hong, of stealing US$22 (S$28) worth of candles, New York Times (NYT) quoted Santa Barbara County attorney Joyce E. Dudley as saying.

When asked if he wanted to press charges, Rodger answered swiftly and decisively: "Yes", the newspaper reported.

Sheriff's deputies were back at Rodger's apartment late on Friday night. This time, Rodger had killed Hong, a 20-year-old student originally from Taipei, along with their other roommate George Chen, 19, and a third man, Weihan Wang, 20, said the report.

All three were students at the University of California, Santa Barbara, and died of stab wounds, apparently inflicted by Rodger just before he took to the streets with three handguns.

The three people killed during the rampage through the streets were also students at the university, the police said. They were Katherine Breann Cooper, 22; Veronika Elizabeth Weiss, 19; and Christopher Ross Michaels-Martinez, 20.

At least 13 people were injured before Rodger took his own life.

Several people who lived in the apartment complex said that both of Rodger's roommates were foreign students who rarely socialised with other residents, NYT reported.

"They are extremely nice, very friendly, and very quiet," said Chris Pollard, 22, a neighbour. "They sat around and played video games," he said. "They were very nice, genuine guys. They were good kids. They went to school and studied a lot. They didn't do anything bad."

In a YouTube video and an online manifesto that he published before the spasm of violence, Rodger spoke of taking revenge on blond sorority girls, and the "brutes" whose company they preferred to his own.

While he wrote at length of clashes with past roommates, he did not seem to have as many conflicts with Hong and Chen. But he wrote he would have to kill his housemates "to secure the entire apartment for myself," adding that he would knock them out with a hammer before slitting their throats.

The sheriff's department did not release any more details about the three young men's deaths, but on Saturday, deputies removed bags of evidence from the apartment, including one bag labeled "2 machetes, 1 knife, 1 hammer", NYT reported.

The newspaper said Hong, who went by the name James, was a computer engineering major and listed Taipei as his hometown on his Facebook profile. He attended Lynbrook High School in San Jose and volunteered at Rainbow Chinese School in Cupertino.

Chen was from Ottawa, Ontario, and attended Leland High School in San Jose, according to his Facebook profile.

Weiss, one of two victims killed outside the sorority house, was described as a dedicated and kind student who had been excited about attending the university. "She was a California girl through and through," said Christine Galvin, the booster president for the school's aquatics program. "When you grow up here, it's an amazing school, and it's far enough from home, but still close to home. It's also difficult to get into. She was really thrilled."

Galvin said the victim was a member of the Westlake High School girls water polo team for four years and served as a team captain and was on the school's swim team for three years. "She was very sweet and friendly to all the girls on the team - very committed, a good team player," the newspaper quoted Galvin as saying. "She was dedicated and kind."

The high school was planning to hold a vigil for her on the pool deck on Monday, said the report.

The other victim killed outside the sorority, Cooper, was about to graduate with a degree in art history, according to media reports. Her friend Courtney Benjamin said Cooper was a painter with an outgoing side. "She was a self-proclaimed princess and I love her for that," Benjamin told The Associated Press. "And I know she has a crown on her head today.

According to the NYT report, Michaels-Martinez graduated from San Luis Obispo High School in 2012. He was a good student who worked on the school newspaper and played on the junior varsity basketball team, the school's principal Leslie O'Connor said on Sunday. He was shot outside at the IV Deli Mart, a popular hangout.

"I always remember that he was a very quiet young man with a close circle of friends," O'Connor said. "He was a very respectful and had a great future ahead of him."

Sam Hassan, 60, whose family owns the IV Deli Mart, said that Michaels-Martinez was part of a group of six people who came into the shop on Friday night. He was the last to enter, and as he was stepping inside, he was shot from behind in the hip. He turned, and was then shot in the chest, falling into the store.

The student was finishing his sophomore year in college and planned to study abroad next year. He wanted to go to law school eventually, O'Connor said.

Many students decided to leave Isla Vista for the rest of the holiday weekend, according to the NYT.

At Giovanni's, a pizzeria in town, the manager said that one of his female employees went home after her distressed mother called, begging her to leave town. Outside the IV Deli Mart, a large memorial popped up, with photographs, flowers and candles offered as a tribute to Michaels-Martinez.

His father, Richard Martinez, said he had a grade-point average of nearly 4.0 in college, and had volunteered at a school cleanup earlier that day. He told his father less than an hour before the shooting how much he enjoyed helping out. "He was really loved by a lot of people," Martinez said. "Things were going very, very well for him in school."