The suspect in the Fort Lauderdale Airport shooting was reportedly known to the FBI

The man authorities suspect of shooting 13 people in the baggage claim of the Fort Lauderdale International Airport on Friday was known to the FBI prior to carrying out the massacre, CBS News reported.

Law enforcement sources told CBS that the suspected assailant, 26-year-old Esteban Santiago, walked into an FBI office in Anchorage, Alaska, in November 2016 claiming he was being forced to fight for ISIS.

Bryan Santiago, the suspect's brother,told The Associated Press that Esteban had been receiving psychological treatment in Alaska, but he did not know what he was being treated for.

Santiago, who was born in New Jersey but moved to Puerto Rico with his family when he was 2 years old, served in Puerto Rico's National Guard and was deployed to Iraq in 2010, Puerto Rico's National Guard spokesman Maj. Paul Dahlen told The Associated Press.

Authorities suspect the man carried out the shooting, which left five people dead, in the baggage claim area of Terminal 2 at Florida's Fort Lauderdale International Airport on Friday.

He is being interviewed by a team of FBI agents and homicide detectives, Broward County Sheriff Scott Israel said in a press conference Friday.

"At this point it looks like he acted alone," Israel said of the suspect. He noted that "it's too early to say either way" whether this was an act of terrorism.