By BRENDAN FARRINGTON and MIKE BALSAMO - The FBI is confirming it is operating on the assumption that the deadly attack at the Pensacola, Florida, naval base by a Saudi flight student was an act of terrorism, while a US official says the gunman had apparently gone on Twitter shortly before the shooting to blast US support of Israel and accuse America of being anti-Muslim.

Investigators are working to establish whether the killer, identified as 2nd Lt. Mohammed Alshamrani, 21, of the Royal Saudi Air Force, acted alone.

Alshamrani fatally shot three people in a classroom building Friday before he was killed by a sheriff's deputy. Florida Gov. Ron DeSantis called Sunday for heightened security vetting of foreign nationals bound for training on US bases.

Download The KTEM-AM Mobile App

By BRENDAN FARRINGTON - A US official says the Saudi student who fatally shot three sailors at Naval Air Station Pensacola had hosted a dinner party earlier in the week to watch videos of mass shootings.

The official says a second Saudi student who attended the party recorded video outside the classroom building where the shooting was happening.

The official also says 10 Saudi students are being held at the base and that several others are unaccounted for.

The official spoke on condition of anonymity after being briefed by federal investigators. The FBI says the dead shooter was a 21-year-old member of the Royal Saudi Air Force.

Download The KTEM-AM Mobile App