The Saudi military student who carried out a deadly shooting spree at a US naval base showed videos of mass shootings at a dinner party the night before the attack, US media has reported.
The shooting Friday in a classroom building at Naval Air Station Pensacola in Florida killed three sailors and wounded eight other people, including two responding sheriff's deputies, before police shot dead the assailant.
The dinner party revelation came as authorities probed whether the shooter had any accomplices.
"We're finding out what took place, whether it's one person or a number of people," President Donald Trump told reporters. "We'll get to the bottom of it very quickly.
The FBI on Saturday formally identified the attacker as Mohammed Alshamrani, 21, a second lieutenant in the Royal Saudi Air Force and a student naval flight officer.
The SITE Intelligence Group, which monitors jihadist media, said he had posted a short manifesto on Twitter prior to the attack that read: "I'm against evil, and America as a whole has turned into a nation of evil." "I hate you because every day you (are) supporting, funding and committing crimes not only against Muslims but also humanity."
Watson's younger brother said the 23-year old, who reported to the base for flight training two weeks ago, "saved countless lives today with his own."