The FBI said on Sunday that it is working under the "presumption" that the shooting at Pensacola Naval Air Station was an "act of terrorism," which will allow investigators to take advantage of certain techniques to "quickly identify and then eliminate any additional threats" to the community.What we know: A gunman identified as Mohammed Alshamrani opened fire at Pensacola Naval Air Station in Florida on Friday, killing three before he was killed by a sheriff’s deputy, per AP. Alshamrani, a second lieutenant in the Royal Saudi Air Force, was attending a pilot training program at the base. An initial assessment from intelligence and counterterrorism officials found that Alshamrani acted alone and did not have ties to international terrorist groups, according to the New York Times. Alshamrani's motives are still unknown.Details: Eight people were injured in the attack, including two sheriff’s deputies who were first responders, according to Escambia County Sheriff David Morgan. Officials initially reported that 12 people were shot.The shooter hosted a dinner party the night before Friday's attack to watch videos of mass shootings, per AP.The shooting took place across two floors of a classroom building at dawn on Friday, per NYT. The shooter used a legally purchased Glock 45 9-mm handgun and had four to six extended magazines in his possession.Multiple Saudi nationals were detained and questioned near the incident. It is not known if they were students in the building during the shooting, per NYT. Three of those detained were seen filming the shooting, but there is currently no immediate indication that they are connected to the gunman.The FBI said investigators are sure Alshamrani was the only gunman.What they're saying: President Trump tweeted that Saudi Arabia's King Salman called him "to express his sincere condolences and give his sympathies to the families and friends" of those killed and injured in the attack in Pensacola. During the call, Salman affirmed that the shooter "does not represent the Saudi people, who count the American people as friends and allies," according to a Saudi Embassy press release on Friday.Salman said he has "directed Saudi security services to cooperate with the relevant  American agencies to uncover information that will help determine the cause of this horrific attack."Of note: Earlier this week, a separate shooting took place Wednesday on another Navy base. A U.S. sailor killed two civilian Defense Department employees at Joint Base Pearl Harbor-Hickam shipyard in Hawaii.The Pensacola base, which employs more than 16,000 military and 7,400 civilian personnel, is among the Navy's most historic and is the home of the Blue Angels flight team.Go deeper: Mass shootings as international incidentsEditor's note: This article has been updated with new information throughout. This is a developing story.