PHILADELPHIA (WPVI) -- When members of the mosque at the Muslim American Society in Hunting Park gathered to pray for the victims of the terrorist attack in New Zealand, there was a level of fear and uneasiness.
"Everybody's scared. I won't even mention it to my kids," said Mazen Khalil, a mosque administrator.
They're concerned about the possibility of copycat incidents.
"Our greatest fear is it's going to inspire other people with the hatred and sentiment inside," said Ribhi Mustafa, the mosque spokesperson.
Brenton Tarrant, the suspect in the shooting that killed 49 in two mosques in New Zealand, is an avowed white supremacist.
While he used Facebook to broadcast his shooting live, experts say he used other lesser-known social media platforms to communicate with other like-minded extremists.
Joel Finkelstein of Princeton studies hate speech on social media and describes some of these sites as 24/7 Klan rallies.
"They have a reality that is completely saturated by white supremacist views and a vision they can turn our world into the reality they're saturated with," said Finkelstein.
Robert Gregory Bowers, the alleged shooter who killed 11 in a Pittsburgh synagogue last year, also found a community of hate on fringe sites that often use cryptic language.
Finkelstein started the Network Contagion Research Institute to help decipher the messages to help law enforcement.
Finkelstein thinks our laws enform envy and politicians need to rethink the way they monitor hate speech online. "I think gearing our justice system to have an understanding of how that mechanism is working to create this plague of haters and murder is critical to being able to police it."
State Senator Sharif Street of Philadelphia's 3rd district said, "When you allow people to hear and absorb so much hate, eventually someone acts on it. I think we have to change the tone and tenor."
Back at the mosque, Mustafa encouraged members to reject fear.
"We're Muslim. We're going to stand tall. We're going to stand proud. Don't shave your beards. Don't take off the hijab," said Mustafa.
After NZ attack, expert warns of "24/7 Klan rallies" on fringe websites
More TOP STORIES News