The Saudi national who fatally shot three sailors at a naval air station in Florida last week unleashed a hail of bullets inside an aviation classroom building as those inside took cover in an assault that unfolded in just a matter of seconds, according to one of the eight people wounded in the attack.

The FBI's Jacksonville office identified the shooter in a statement Saturday night as Mohammed Alshamrani, 21, and released a photo of him. Investigators said he was a 2nd Lt. in the Royal Saudi Air Force and was a student naval flight officer of Naval Aviation Schools Command.

Officials investigating the attack are still working to determine whether it was an act of terrorism, while President Trump said Saturday that the U.S. would “immediately” conduct a review of the training procedures and pledged to “get to the bottom” of what happened.

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Officials said that Alshamrani opened fire inside a classroom at the naval base around 6:30 a.m. Friday, killing three people and wounding two sheriff's deputies, one in the arm and one in the knee, before one of the deputies killed him. Eight others were also hurt.

This undated photo provided by the FBI shows Mohammed Alshamrani. The Saudi student opened fire inside a classroom at Naval Air Station Pensacola on Friday before one of the deputies killed him. (FBI via AP)

One of those injured in the attack, Navy airman and assistant high school wrestling coach Ryan Blackwell, told the Pensacola News Journal Saturday from the intensive care unit at Baptist Hospital he heard gunshots down the hall then took cover along with two colleagues.

“He didn’t come inside,” Blackwell told the newspaper. “He just shot through the door.”

Blackwell said the gunfire lasted between 15 and 20 seconds. The bullets shattered the glass of the office where Blackwell and others were taking cover. The 27-year-old said he used his body to shield a female colleague. All three of the workers in the office were shot, with Blackwell struck in the right arm and bloodied.

“My adrenaline was pumping so much,” he told the newspaper. “I wasn’t worried about being shot. I was worried about getting us to safety and getting us out of there.”

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Blackwell used his belt as a tourniquet to stop the bleeding and contacted another co-worker who had not arrived at the office to transport the three injured Navy airmen to the main gate of the naval air station, where they were transported by police to the hospital.

“We could have been three more casualties if we didn’t escape,” Blackwell told the newspaper.

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The Navy on Saturday identified the three victims of the NAS Pensacola shooting as Ensign Joshua Kaleb Watson, 23, of Coffee, Ala.; Airman Mohammed Sameh Haitham, 19, of St. Petersburg, Fla.; and Airman Apprentice Cameron Scott Walters, 21, of Richmond Hill, Ga.

Joshua Watson was killed Friday in the Pensacola naval base shooting, according to his family.

"The Sailors that lost their lives in the line of duty showed exceptional heroism and bravery in the face of evil," said the Navy chief of information in a statement. "When confronted, they didn't run from danger; they ran towards it and saved lives. If not for their actions, and the actions of the Naval Security Force that were the first responders on the scene, this incident could have been far worse."

This undated photo provided by the U.S. Navy shows Airman Mohammed Sameh Haitham, from St. Petersburg, Fla. He has been identified as one of the victims of the shooting Friday, Dec. 6, 2019, at Naval Air Station Pensacola, Fla. (U.S. Navy via AP)

The U.S. Northern Command (Northcom) has called for increased random security checks at all sites across Northern Command. The order follows the deadly shootings last week at Joint Base Pearl Harbor-Hickam in Hawaii and the Naval Air Station (NAS) Pensacola in Florida.

Airman Apprentice Cameron Scott Walters was among the victims. (US Navy Photo)

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"Given the recent attacks at two military installations, the Commander, U.S. Northern Command has directed all DoD [Defense Department] installations, facilities and units within the U.S. Northern Command area of responsibility to immediately assess force protection measures and implement increased random security measures appropriate for their facilities,” Lt. Cmdr. Michael Hatfield told Fox News.

"The advisory also told leaders to remind their workforce to remain alert and if they see something, to say something by immediately reporting to appropriate authorities any suspicious activity they may observe," Hatfield said.

Fox News' Marisa Schultz, Paulina Dedaj, Morgan Phillips, and The Associated Press contributed to this report.