Iraq war veteran who shot dead five at Florida airport had gun returned last month after it was confiscated following mental health assessment

News reported authorities seized three weapons and a computer in 2011 or 2012 with regards to child sex abuse images but didn't file any charges.

It comes as the FBI said it had not ruled out a terror motive in the Fort Lauderdale airport shooting.

Initial reports said the suspected killer rowed with a fellow passenger during his journey from Alaska.

Reports had suggested the mass shooting at Fort Lauderdale airport's baggage reclaim may have been sparked by the air rage incident.

But authorities said on Saturday said there are no signs there was any altercation on the flight or at baggage claim prior to the attack.

The 26-year-old Iraq veteran, who is today being held in custody, was said to be known to authorities after he reportedly walked into the FBI office "claiming he was being forced to fight for ISIS".

He is said to have spoken to authorities about the terror group in November.

George Piro, special agent in charge of the FBI in Miami, said he cooperated with investigators during an interview that lasted several hours overnight.

Santiago told officials he was hearing voices in his head, some of which were telling him to join ISIS and watch their videos, and was taken to hospital for a mental health evaluation.

Santiago, who also told the FBI the government controlled his mind, gunned down 13 people at Fort Lauderdale airport killing five and injuring eight.

Florida Governor Rick Scott said some of the victims were still in surgery fighting for their lives after Friday's rampage in the crowded baggage claim area.

The suspect's aunt Maria Ruiz Rivera claimed the alleged shooter "lost his mind" while fighting in Iraq.

When quizzed why Santiago may have opened fire at passengers, her husband, Hernan Rivera, said: "No idea. Only thing I could tell you was when he came out of Iraq, he wasn't feeling too good."

Chilling photos posted on Instagram show Santiago posing next to UK landmarks in a jacket emblazoned with a skull and cross.

One image appears to show the alleged shooter outside Bath Abbey, but it is captioned "#London".

His Instagram bio reads: "Here's to finding whether or not your mission on earth is finished ; if your still alive ... It isn't."

Santiago, who is accused of opening fire at passengers with a gun he had checked in his luggage, was reportedly receiving psychological treatment while living in Alaska.

Eight people were rushed to hospital after the mass shooting in Terminal 2's baggage reclaim.

Santiago reportedly loaded the gun, which he had carried on a flight from Alaska to Florida, via Minneapolis, in the bathroom and came out shooting.

He is not thought to have said anything during the mass shooting.

Santiago is thought to have flown into Fort Lauderdale on a Delta flight from Anchorage, Alaska.

Senator Bill Nelson named Santiago as the suspect on news channel MSNBC and said he was carrying military identification.

A military spokeswoman says the suspect in a deadly shooting at the Fort Lauderdale, Florida, airport received a general discharge from the Alaska Army National Guard last year for unsatisfactory performance.

Lt. Col. Candis Olmstead did not release details about 26-year-old Esteban Santiago's discharge in August 2016. Olmstead said that he joined the Guard in November 2014.

Santiago is from New Jersey, but his most recent address is listed as Naples, Florida.

He has a history of mental health problems, according to NBC News.

His brother said Santiago received psychological treatment in Alaska and had served in the Guard.

Sheriff Scott Israel says Santiago was not harmed and law enforcement did not fire any shots.

A witness described the shooter as a slender, gun-wielding man in a blue "Star Wars" t-shirt.

John Schichler told MSNBC the suspect was able to reload his gun at least once during the attack.

Broward County Mayor Barbara Sharief said: "We have no evidence at this time that he was acting with anyone else. He is currently in custody and we're investigating."

Witness Chenet Nerette said the gunman "took a knee right before he opened fire", suggesting he was preparing for the massacre.

Another witness described the airport as "like a war zone" after the horrifying shooting.

Horrifying video footage shows passengers cowering in fear in the aftermath of the massacre.

Panicked witnesses were seen crouching near the floor and desperately try to flee the scene after shots ring out.

Terrifying Twitter reports described "everyone running" after the shots were fired shortly before 6pm.

Former White House Press Secretary Ari Fleischer tweeted: "I'm at the Ft. Lauderdale Airport. Shots have been fired. Everyone is running."

He added: "Police said there is one shooter and five victims."

President-elect Donald Trump tweeted: "Monitoring the terrible situation in Florida. Just spoke to Governor Scott. Thoughts and prayers for all. Stay safe!"