The gunman - wearing a Star Wars T-shirt - was taken into custody and has since been identified as 26-year-old Esteban Santiago. Santiago flew into the airport from Anchorage, Alaska (with a layover in Minneapolis, St. Paul) on Delta flight 2182, and checked a gun for the flight.
After claiming his bag, he loaded the gun in a bathroom and then opened fire on the baggage claim area, Broward County Commissioner Chip LaMarca said. NBC News reports that Santiago had a history of mental problems, but had reportedly been getting treatment.
Sources have told CBS news that Santiago walked into an ABI office in Anchorage in November last year claiming he was being forced to fight for ISIS.
His most recent address was in Naples, but he lived in Anchorage from 2014 to 2016, where his girlfriend and child continue to live. He is also from New Jersey.
Santiago was an Iraq veteran having served in the country for one year before being honorably discharged in August last year, the Army Criminal Investigation Division confirmed. He had also been a combat engineer in the Army National Guard.
His aunt Maria Ruiz told NorthJersey.com that Santiago had returned from Iraq acting strangely but had seemed happy after the birth of his child last year.
Santiago's brother Bryan Santiago said he could have suffered a 'flashback' from his time in Iraq, despite never being diagnosed with PTSD, NBC reports.
The motive for the shooting is still not known, but Florida Sen. Marco Rubio told CNN that Santiago may have gotten into an altercation on his flight earlier that morning.
'I know that was mentioned as a potential cause and they wanted to kind of look into that a little further and get to that point,' Rubio said.
Santiago's brother said he had been fighting with people back in Alaska, including his girlfriend who he was having relationship issues with.
He said Santiago, who was 'was pro-America', has not spoken to his family for several weeks, which was unusual.
Sources also told ABC News that Santiago was contacted by the FBI after an employer back in Alaska raised concerns about certain things he had said. After that meeting, Santiago started getting treatment for his mental health issues.