[新闻背景]LOS ANGELES — American Sikhs have been mourning the victims of the mass shooting at a Sikh temple in Wisconsin - and are trying to comprehend an act that seems senseless. The shooter's motives are unclear, but one organization that monitors hate groups points to the Internet as a breeding ground for racial hatred.

In the Los Angeles suburb of Sikhs and other community members gathered for a vigil to remember the victims of the Wisconsin shooting.

Some also tried to understand what motivated the accused shooter, Wade Michael Page.

California temple member Nachhatar Singh Bhullar calls the act senseless.

"It could happen anywhere. Somebody can come anywhere and do those things," he said.

But researchers into hate groups say Page had ties to music groups with a white supremacist message and they speculate that his hatred sparked the rampage.

Tim Zaal, 48, recognizes the message. He came to the Sikh temple to offer condolences, but says he once viewed all dark-skinned people with hatred. He spent a year in jail for attacking an Iranian couple and has been involved in other hate crimes. In the 1980s, he was a skinhead and organizer for the neo-Nazi group White Aryan Resistance.

"The white racialist movement was moving into a different direction. Rather than have all these great big organizations, they started to operate in these little cells," he said.

And they started organizing online.

Rick Eaton is a researcher on hate groups with the Simon Wiesenthal Center, which monitors social sites such as Twitter and Facebook, and distributes an online research app - or application - to law enforcement agencies.

He says a world of hatred, little seen by most Americans, thrives on racist music, epithets and symbols.

"The name of the song is Keep Fighting, and it says their job is to keep fighting and if you don't, I'll kill you myself," he said.

Rabbi Abraham Cooper, associate dean of the Simon Wiesenthal Center, says through music and diatribes, the online sites spread ideas, attract revenue and recruits, and strengthen their commitment to a set of beliefs.

“It's empowerment, it's validation," he said.

He says, for people on the fringe, the sites create the illusion of a mass movement.

There are limits to what law enforcement can do in the absence of a crime, no matter how offensive the hate speech, says Teresa Carlson of the Federal Bureau of Investigation.

“Until somebody actually threatens, there’s a threat of force or violence, we can not open an investigation," she said.

Rabbi Cooper says companies that dominate the Internet need to do more.

"The social networking on the Internet could and should be doing a lot more to marginalize the message, messages and messengers of hatred and intolerance and terrorism," he said.

Meanwhile, the Sikhs of California are trying to understand how a quiet house of worship could become the scene of such a tragedy.