The 26-year-old man accused of opening fire at Fort Lauderdale-Hollywood International Airport earlier this month pleaded not guilty to 22 counts at his arraignment in a federal court on Monday.

Esteban Santiago Ruiz allegedly traveled from Alaska and started firing in the Florida airport's crowded baggage claim area. Investigators say he continued until he ran out of ammunition, then dropped his weapon and was arrested by law enforcement officers.

Five people were killed and six were injured during the attack. According to the criminal complaint, Santiago told investigators that he planned the assault.

"Esteban Santiago, shackled and wearing a prison jumpsuit, stood while Magistrate Judge Barry Seltzer read all 22 counts," NPR's Greg Allen reports from the court in Fort Lauderdale. Here's more:

"Seltzer explained to Santiago each count, and the maximum penalty. With the combined counts, if found guilty, Santiago faces a maximum penalty of death or life in prison. Santiago told the judge he understood each of the charges against him and the penalties. His lawyer said Santiago pleaded not guilty to all charges. A date will now be set for a jury trial."

Seltzer repeatedly emphasized the victims' names as he read the entire indictment aloud, according to The Associated Press.

The indictment "includes five counts of 'violence at an international airport resulting in death,' as well as numerous weapons charges for allegedly firing a Walther 9-millimeter pistol," The Two-Way reported.

Santiago served in the National Guard, including a tour in Iraq, and was discharged for unsatisfactory performance.

Authorities say Santiago also suffered from mental health issues. He sought help from the FBI in Anchorage, Alaska, last year, saying he was having "terroristic thoughts." He was taken to a mental health facility but was released.

The Two-Way has compiled a rundown of what we know about Santiago, found here.

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