Ahead of attack that killed three US sailors and injured eight other people, shooter Mohammed Alshamrani shared anti-American and anti-Israeli messages on social media

Qassim al-Rimi had claimed responsibility for last year's deadly shooting at Naval Air Station Pensacola where a Saudi aviation trainee killed three American sailors

Shooter motivated by jihadist ideology, visited 9/11 memorial and posted anti-US and anti-Israel remarks just hours before killing 3 people; Apple refusing to help unlock his phone

Mohammed Alshamrani apparently used Twitter account under name similar to his own to criticize US policy, but investigators not sure if he wrote content himself or just shared it

Officials say they cannot yet link attack to terror as motive in deadly shooting probed; 10 Saudi students being held on base and other unaccounted for

Second shooting at a US Navy base this week, 11 people injured including two sheriff's deputies who were first to respond, one of whom killed the shooter