FORT LAUDERDALE, Fla. -- Thirteen people were shot Friday afternoon at Fort Lauderdale-Hollywood Int'l Airport in Florida. Five of those victims died after a gunman opened fire in the Terminal 2 baggage claim area.

The suspect has been identified as 26-year-old Esteban Santiago. A county official says Santiago pulled a gun out of a checked bag, loaded it in a bathroom and started shooting.

"He was just as calm as can be. He just started shooting. He wasn't frantic," one witness told CBS.

"He was not screaming anything, not shouting anything," another witness said.

Santiago re-loaded the semi-automatic pistol twice.

"He was not targeting anyone. He was just shooting at random," witness Mark Lea said. "He was just picking off things like target practice."

Esteben, who was carrying a military ID, was a passenger on a flight that originated in Anchorage, Alaska.

MORE: 911 calls from Ft. Lauderdale airport shooting released

His brother says Esteben had been receiving psychological treatment while living in Alaska. Bryan Santiago tells The Associated Press that his family got a call in recent months from Esteben Santiago's girlfriend alerting them to the situation.

CBS News reports he was admitted to a mental hospital after telling Anchorage police that the government and CIA were spying on him. He said he was being forced to watch ISIS videos.

Esteben Santiago pulled a gun out of a checked bag, loaded it in a bathroom and started shooting, according to investigators. 

Sheriff Scott Israel said authorities had not established a motive for the shooting and that it was too early to declare it a terrorist act.

Bryan Santiago said his brother was born in New Jersey but moved to the U.S. territory of Puerto Rico when he was 2 years old.

He said Esteban Santiago grew up in the southern coastal town of Penuelas and served with the island's National Guard for a couple of years.

He was deployed to Iraq in 2010 and spent a year there with the 130th Engineer Battalion, the 1013th engineer company out of Aguadilla, according to Puerto Rico National Guard spokesman Maj. Paul Dahlen.

Santiago and his girlfriend have a 3-month-old son. The suspect worked in security in Anchorage.

Hundreds of people were evacuated after a shooting at Fort Lauderdale Airport on Friday, Feb. 6. (WFOR)

Hundreds of passengers were evacuated to the tarmac after the shooting. Others were kept on planes for hours.

Hours after the incident, the TSA tweeted there was still an active shooter situation at the airport. The Broward County Sheriff''s office tweeted there were unconfirmed reports of more shots fired.

People could be seen running from the airport and taking cover behind cars or anything they could find. Journalists were also moved away from the airport by police.

But it turned out to be a false alarm, according to the sheriff's office.

Early word on the shooting came from a tweet by Ari Fleischer, former White House spokesman for President George W. Bush. "I'm at the Ft. Lauderdale Airport," Fleischer tweets. "Shots have been fired. Everyone is running."

Fleischer later tweeted that all seemed calm but police weren't allowing people to leave the part of the airport where he is.

People were finally allowed to leave the airport six hours after the shooting. The airport is scheduled to reopen at 5 a.m. Saturday.

Santiago will face federal charges, officials said in a press conference Friday evening. He is due in court on Monday.