Elliot Rodger’s parents tried to stop him after receiving an email minutes before killing six people in Santa Barbara on Friday, says a family friend.

They raced to Isla Vista but heard radio reports on the shootings as they drove, friend Simon Astaire told US media.

Elliot Rodger, 22, warned of his intentions in his emailed manifesto and a YouTube video posted the day before.

Hundreds gathered at a memorial service in the college town to mourn the dead.

Three more of the victims were named on Sunday night – Cheng Yuan Hong, 20, George Chen, 19, and Weihan Wang, 20, were stabbed in Elliot Rodger’s apartment.

They were his first victims before he killed three more and wounded 13 others in a shooting rampage.

Elliot Rodger died after speeding through the town in his black BMW, exchanging fire with police, authorities said.

He was found dead in his car from a gunshot wound to the head, believed to be self-inflicted, with three legally purchased semi-automatic weapons.

Moments before he began opening fire, Elliot Rodger emailed his parents, therapist and others to inform them of his intentions in a 140-page “manifesto” entitled Day of Retribution.

Elliot Rodger’s mother Li Chin called the police before she and ex-husband Peter Rodger raced to Isla Vista from Los Angeles in separate cars, but heard en route about the shooting, family friend Simon Astaire told US media.

In a video posted on YouTube on Thursday, Elliot Rodger spoke of his plan to “slaughter” women at a sorority house at the University of California at Santa Barbara.

He described the rejection he felt because he had never been able to attract girls, and how he intended to exact revenge.

Santa Barbara County Sheriff Bill Brown said his department had visited Elliot Rodger at the end of April at the request of his family when they saw disturbing videos he recorded but officers found him to be polite and courteous, and no further action was taken.

Elliot Rodger had seen therapists off and on since he was nine years old and possessed “an underlying sadness”, Simon Astaire told Reuters. There was no suggestion he had any interest in guns.

In his manifesto, he said he feared police would foil his plot when they visited him.

“I had the striking and devastating fear that someone had somehow discovered what I was planning to do, and reported me for it,” Elliot Rodger wrote.

“If that was the case, the police would have searched my room, found all of my guns and weapons, along with my writings about what I plan to do with them.

“I would have been thrown in jail, denied of the chance to exact revenge on my enemies. I can’t imagine a hell darker than that.”

Katherine Cooper, 22, Veronika Weiss, 19, and Christopher Martinez, 20, were earlier named as Elliot Rodger’s shootings victims.

In an emotional statement, Ricardo Martinez said the death of his son Christopher had left his family “lost and broken”, and he blamed “craven politicians” and gun rights advocates.

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A CCTV footage released by CNN showed the moment terrified shoppers threw themselves to the ground as gunman Elliot Rodger burst into Santa Barbara grocery store and opened fire.

Elliot Rodger, 22, left six people dead in a knife and gun rampage in the Californian university town of Isla Vista on Friday night, before apparently shooting himself in the head after a firefight with police.

His killing spree began after he posted a chilling video on YouTube, titled Elliot Rodger’s Retribution, in which he threatened to “slaughter” women who had rebuffed him.

It’s believed that at sometime on Friday Elliot Rodger stabbed three men to death at his apartment, before driving to a sorority house near the University of California at Santa Barbara and shooting dead two women – Veronica Weiss and Katherine Cooper.

At 9.30 PM Elliot Rodger entered a grocery store, shooting and killing his sixth victim – Christopher Michael-Martinez.

After the killing at the grocery store, Elliot Rodger fled and exchanged fire with officers.

At 9.37 PM Elliot Rodger crashed into a police car, and was found dead from an apparent gunshot wound to the head.

Also in the car were three legally purchased semiautomatic guns – two Sig Sauers, a Glock, and more than 400 rounds of ammunition.

Santa Barbara County Sheriff Bill Brown told a news conference that the killings were “obviously the work of a madman”, and it was “very very apparent he was severely mentally disturbed”.

The community college student had been seen by a variety of health care professionals, and Bill Brown said his department had been in contact with him three times before Friday.

In July 2013, police spoke to Elliot Rodger while he was in hospital where he claimed to be the victim of an assault, but officers thought later he could have been the aggressor.

On January 15 this year, Elliot Rodger called police and accused a room-mate of stealing three candles worth $22, and made a citizen’s arrest for petty theft.

On April 30, police contacted Elliot Rodger at home after his family asked authorities to check on his welfare, but found him to be “polite and courteous”.

Bill Brown said: “He downplayed the concerns for his welfare and the deputies cleared the call.”

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Santa Barbara deputies were convinced that Elliot Rodger, who killed six innocent people and himself during a shooting rampage in Isla Vista Friday, wasn’t a threat following a welfare check last month, Sheriff Bill Brown revealed.

Concerned family members of Elliot Rodger contacted mental health professionals in April, Bill Brown said. When his agency was notified, deputies were sent to check on Elliot Rodger.

“He convinced them that it was all a misunderstanding,” Bill Brown told NBC4.

Though Elliot Rodger told deputies that he was having social problems and was likely going to leave school, “he was able to convince them that he was not a threat to himself or to anyone else at the time”.

On Friday, Elliot Rodger stabbed three people in his apartment and then killed three more in a killing spree that stretched for several blocks in the small beachside community.

Prior to the rampage, Elliot Rodger recounted his life in detail, dwelling on rejection by women and laying out his plans for vengeance. His plans for the rampage are detailed in the manifesto, including steps to kill people first at his apartment, then throughout Isla Vista before taking his own life.

Authorities hope to learn from the miscues between Santa Barbara County’s mental health services and law enforcement to prevent tragedies like this from happening again, Bill Brown said.

“Certainly in hindsight, we wish that had happened, but unfortunately in this case it didn’t,” he said.

Bill Brown said another key in stopping situations like Friday’s shooting before they occur rests with mental health professionals who have a deep insight and can identify potentially dangerous issues.

“It’s a delicate balance that has to be achieved because you want to be able to intervene, you want to be able to prevent something like this,” Bill Brown said.

“You also want to encourage people to seek mental health treatment, and if you stigmatize people by placing restrictions on them…that actually serves as a deterrent for people seeking mental health treatment.”

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