Saudi Arabian military students in the United States will continue classroom instruction but operational training is halted pending a security review, senior Defense Department officials said.

Mohammed Alshamrani, a 21-year-old lieutenant in the Saudi Royal Air Force, opened fire in a classroom at Pensacola Naval Air Station in Florida on Friday, killing three American sailors and wounding eight other people before being shot dead by police.

Deputy Secretary of Defense David Norquist ordered a review to be completed within 10 days of policies for screening foreign students, Pentagon officials said.

The move applies to all Saudi military students currently undergoing training in the United States.

"The ones that are pilots will be grounded," an official said.

Alshamrani, who was armed with a lawfully purchased Glock 9mm handgun, is reported to have posted a manifesto on Twitter before the shooting denouncing America as "a nation of evil."

White House National Security Advisor Robert O'Brien has said the FBI investigation was ongoing but "to me, it appears to be a terrorist attack."

The shooting struck a nerve in the United States with its echoes of the September 11, 2001 attacks, in which Saudi citizens accounted for 15 of the 19 hijackers that flew airliners into the World Trade Center and the Pentagon.