WASHINGTON - The Florida airport shooting suspect was being treated in the US state of Alaska after complaining of hearing voices and claiming that the CIA was forcing him to join ISIS, according to media reports citing federal officials.

Esteban Santiago, 26, was identified as the gunman who opened fire at a baggage claim at the Fort Lauderdale-Hollywood International Airport on Friday, killing five people and wounding eight.

The suspect was born in New Jersey but moved to Puerto Rico with his family and was raised there, according to media reports.

He joined the Puerto Rico National Guard in December 2007, and served in Iraq from April 2010 to February 2011 as a combat engineer, according to the Alaska National Guard.

He was in the Army Reserves before joining the Alaska National Guard two years ago and got a general discharge Aug. 16, 2016, for unsatisfactory performance, a spokesman for the Alaska guard said. He was a private first class when he was discharged, the Guard said.

Witnesses said the gunman shot his victims at random until he ran out of bullets, then got on the ground and waited for police.

In November, Santiago walked into the FBI's office in Anchorage and claimed his mind was being controlled by a US intelligence agency and the CIA was forcing him to watch ISIS videos, federal law enforcement officials told NBC News.

Santiago was clear that he didn't intend to harm anyone, but the FBI was concerned by his erratic behaviour and called police and he was taken to a mental health facility for an evaluation, FBI Special Agent in Charge George Piro of the Miami division told reporters Friday night.

"We looked at his contacts, we did our interagency checks and everything and at that point we closed our assessment," Piro said.

A spokeswoman for the Anchorage Police Department referred all questions about Santiago to the FBI.

US OFFICIALS NOT RULING

OUT 'TERRORISM'

AFP adds: The US authorities are not ruling out "the terrorism angle" as a potential motive of the Iraq war veteran.

Police interrogated the suspect, 26-year-old Esteban Santiago, throughout much of the night after the shooting rampage that killed five people, wounded six and sent thousands scrambling for safety before the authorities shut down the airport, a major gateway to the Caribbean and Latin America.

"We continue to look at all avenues and all motives for this horrific attack," George Piro, the special agent in charge of Miami's FBI field office, told journalists. "We are continuing to look at the terrorism angle in regards to the potential motivation behind this attack."

Piro said the suspect appeared to be acting alone and that "every indication is that he did follow (Transportation Security Administration) procedures in checking in the weapon," a nine-millimeter semi-automatic handgun he had declared and stowed inside his checked luggage.

Santiago had traveled from Alaska to Fort Lauderdale, with a stopover in Minneapolis, Minnesota.

Following the initial gunshots, a deputy officer came into contact with the gunman after approximately 70 to 80 seconds, Broward County Sheriff Scott Israel told reporters.

Congresswoman Debbie Wasserman Schultz, who represents the district that includes the airport, said the incident brought into question federal rules that allow firearms to be carried on a plane in checked baggage.

"We need to review not only the question of should people be able to travel with the firearm or even if they're in checked baggage, but we need to take a hard look at the security around baggage claim areas and not just leave it at that," she said.

"It's been pointed out that there are many unsecure areas in facilities that the public travels."

The international flight hub was open again Saturday, aiming to run at about 85 percent of its normal capacity, according to the airport director.

Airport personnel were also busy conducting the complicated task of returning nearly 20,000 pieces of luggage and other personal items abandoned by passengers fleeing at the time of the shooting, officials said.