Three individuals were killed at the Islamic Center of San Diego by two teenage gunmen who subsequently took their own lives.Security guard Amin Abdullah prevented further tragedy by delaying the attackers, while investigators later recovered a manifesto filled with extreme hate rhetoric.Federal and local authorities are currently probing the radicalization process and the origins of the thirty firearms seized from the suspects.Community leaders and officials continue to condemn the violence while examining the suspects' online activity and extremist ties.