A Saudi aviation student who killed three people in a mass shooting on a Pensacola, Florida, naval base on Friday hosted a party earlier in the week where he showed videos of mass shootings, the Associated Press reported.

The Saudi national who was training at the Naval Air Station Pensacola opened fire at the base on Friday, killing three and injuring eight more. He was also shot dead by deputies, the local sheriff’s department confirmed.

Although initial reports indicated that the shooter was believed to have acted alone, a U.S. official told the AP that he screened the violent videos at a dinner party, and that another Saudi student is believed to have been recording during the shooting.

A Twitter account with the same name as the shooter, whom The New York Times identified as Mohammed Saeed Alshamrani, posted a message shortly before the shooting calling the U.S. a “nation of evil” for supporting Israel, according to SITE intelligence group, which tracks extremist activity. One of the three tweets on the shooter’s page reportedly quoted former al-Qaeda leader Osama bin Laden.

Three other students attended the party hosted by Alshamrani, who is a member of Saudi Arabia’s Air Force, the week of the attack, according to the U.S. official who cited a briefing by federal investigators. One of those three attendees filmed the shooting from outside the building, the AP reported. Two other students reportedly watched the shooting from a nearby car.

Ten of Alshamrani’s fellow Saudi students are being held at the base, while others reportedly remained unaccounted for early Saturday afternoon.

U.S. officials are reportedly investigating whether the shooting was an act of terrorism. An official told the Times that Alshamrani did not appear to have any ties to international terror groups and seemed to have self-radicalized.

In a Saturday press conference, President Donald Trump said investigators were “finding out what took place, whether it’s one person or a number of people.”

Alshamrani used a Glock with an extended magazine, which he had purchased locally, The New York Times reported. He carried as many as six additional magazines.

The base currently hosts approximately 200 international students, and Saudi and American students attend the same early trainings before separating into their own programs later on, according to the Times. Alshamrani began training in the U.S. in August 2017, and was scheduled to conclude training next August, officials told the AP. The shooting likely caught students during a busy period shortly before 7 a.m., near the beginning of classes.

One of the three victims was 23-year-old Joshua Kaleb Watson, his brother confirmed Saturday.

In a Facebook post, Watson’s brother Adam credited him with saving “countless lives” after he was shot by escaping the building and giving first responders information on the shooter inside. Watson later died in the hospital. It was his dream to serve in the Navy, his family said.

Editor’s Note: This article has been updated to reflect that the dinner party was held earlier in the week, not the night before the shooting, as the Associated Press initially reported.