A lone shooter was responsible for the attack at the Fort Lauderdale International Airport.
US authorities are not ruling out "the terrorism angle" as a potential motive of the Iraq war veteran accused of killing five people at the Fort Lauderdale International Airport, officials said Saturday.
Esteban Santiago, 26, was charged in the shooting rampage Friday that also wounded six and sent thousands scrambling for safety before authorities shut down the airport in Florida, a major gateway to the Caribbean and Latin America.
"We continue to look at all avenues and all motives for this horrific attack," said George Piro, the special agent in charge of Miami's FBI field office. "We are continuing to look at the terrorism angle in regards to the potential motivation behind this attack."
Santiago was charged Saturday with firearms offenses and carrying out an act of violence at an airport, federal prosecutor Wifredo Ferrer said in a statement. If convicted, he could face the death penalty or life in prison.
The suspect was scheduled to make an initial court appearance on Monday.
Separate murder charges could be forthcoming from state prosecutors, but no decision has been made yet, a spokesman for Broward County State Attorney Mike Satz told the local Sun Sentinel newspaper.
Piro said the suspect appeared to be acting alone and that "every indication is that he did follow (Transportation Security Administration) procedures in flying with the weapon," a nine-millimeter semi-automatic handgun he had declared and stowed inside his checked luggage.
The incident occurred in the baggage claim area of Terminal 2. Authorities said the gunman loaded his gun in a bathroom, then opened fire on passengers collecting their luggage.
"Santiago started shooting, aiming at his victims' heads until he was out of ammunition," Ferrer said.
Santiago had traveled from Alaska to Fort Lauderdale, with a stopover in Minneapolis, Minnesota.
In November, Santiago had walked into the FBI's Anchorage office exhibiting "erratic behavior" that led agents to contact local police, who took him to a medical facility for a mental health evaluation, Piro said.
However, he was not placed on a no-fly list, Piro added.
'He said he saw things'A former member of the Puerto Rico and Alaska National Guard, Santiago served in Iraq from April 2010 to February 2011. He ended his service in August.
The suspect had complained to the FBI that his mind was being controlled by national intelligence agencies, which were forcing him to watch ISIS terrorist videos.
Santiago allegedly opened fire shortly before 1:00 pm (1800 GMT) Friday.
A deputy officer came into contact with the gunman after approximately 70 to 80 seconds, and authorities were able to detain him without firing any shots, Broward County Sheriff Scott Israel told reporters.
An aunt, Maria Luisa Ruiz, told the NorthJersey.com news site that Santiago became a father to a baby boy in September -- and that he was having mental problems.
"Like a month ago, it was like he lost his mind," Ruiz said. "He said he saw things."
"My family and I are in shock right now," she added. "It's sad, but we have to confront the situation."
Authorities have not identified any victims, but three named in media reports were all getting ready to set off on cruises.
They included 84-year-old grandmother Olga Woltering of Marietta, Georgia, the Sun Sentinel reported. The British native and her 90-year-old husband were going on a cruise with family to celebrate his birthday.
"Olga was so charming, calling everybody 'Lovey' or 'Love' in her unmistakable British accent," the Catholic Church of the Transfiguration, where Woltering was an active member, said on its website.
Terry Andres, 62, was going on vacation with his wife of nearly four decades, Ann, the Palm Beach Post reported. He lived in Virginia Beach, Virginia and worked at the Norfolk Naval Shipyard.
Michael and Kari Oehme, in their 50s from Council Bluffs, Iowa, were both shot, the Miami Herald said. Michael Oehme was killed, while his wife was wounded in the shoulder.
In addition to those killed and wounded by the gunman, as many as 40 people went to the hospital for various other injuries such as sprains, Israel said. Three of the wounded were still in the intensive care unit.
Checking weaponsThe shooting renewed anxieties about airport security -- a concern that has loomed large in the post-9/11 era -- and shed new light on ongoing US gun-control debates.
The Transportation Security Administration -- the agency responsible for security at United States airports -- allows passengers to travel with unloaded firearms and ammunition as checked baggage.
Congresswoman Debbie Wasserman Schultz, who represents the Florida district that includes the airport, said the rules need to be reexamined.
Speaking to CNN, she said the incident should prompt close review of "whether or not you should be allowed to check a firearm at all" -- as well as how passengers should be able to retrieve checked weapons after landing.
"If there is still exposure to the traveling public of someone who wishes to do them harm and, like this individual, was reunited with their firearm and was able to wreak havoc... it absolutely needs to be addressed."
Senator Chris Murphy, a Democrat from Connecticut, rebuked the government for not taking legislative action to tighten gun laws.
"Political cowardice is the accomplice of every mass shooter," he wrote on Twitter.
"The utter silence of Congress in the face of this carnage has become consent."
The Fort Lauderdale airport was open Saturday. Staff there were trying to return nearly 20,000 pieces of luggage and other personal items abandoned by passengers fleeing the shooting.