New York — In the aftermath of the mass shooting in El Paso, Texas, attention is turning to where hate groups spread their message online — and what the FBI is doing to prevent the next attack.

Minutes before opening fire, investigators believe accused El Paso shooter Patrick Crusius posted a manifesto to 8chan, an online message board used by extremists.

Sunday night, 8chan was kicked off its cloud service. But George Selim, a former Department of Homeland Security counterterrorism official, said that won't silence hate talk.

"They're going to find another forum to gravitate to. They've been systematically kicked off of Facebook and Twitter and other mainstream channels for the past several years. They've gravitated to other places and other forums where there are less rules and it's less restrictive," Selim said.

Hate crimes are on the rise, up 9% in America's 30 largest cities last year, according to The Center for the Study of Hate and Extremism at California State University, San Bernardino. The problem is growing so acute, the FBI released a rare statement Sunday, warning of "the continued threat posed by domestic violent extremists and perpetrators of hate crimes."

The FBI said it has 5,000 open terrorism cases and 850 of those are domestic.

To prevent attacks like the ones in El Paso and Dayton, the FBI Behavioral Analysis Unit meets regularly to try to intervene before there is violence. CBS News attended one session, where they discussed the case of a 13-year-old boy who obtained his step-father's guns and expressed an interest in school shootings. It was his mother who tipped off police.

The FBI said they remain concerned this weekend's attacks could inspire domestic extremists to engage in more acts of violence.