The man arrested at the Atlanta airport after his family reported he had threatened to shoot up the terminal is now facing federal charges, authorities say.

At a press conference discussing the arrest on Tuesday, Atlanta Police Chief Darren Schierbaum said that 49-year-old Billy Joe Cagle is in the process of being transported into federal custody.

Cagle was charged with making terroristic threats, criminal attempt to commit aggravated assault, possession of a firearm during the commission of a felony, and possession of a firearm by a felon. On Tuesday night, prosecutors announced they had charged Cagle with attempted violence at an international airport, interstate communications containing threats, and possession of a firearm as a felon.

"As alleged in this complaint, Cagle senselessly threatened to do heinous violence to innocent travelers, at the world's busiest airport, with a high-powered weapon that he had no legal right to possess," said U.S. Attorney Theodore S. Hertzberg. "Thanks to the vigilance of other citizens and the quick action of law enforcement, a horrible tragedy was averted."

Investigators say the FBI is working to learn how he obtained the semi-automatic rifle that was found in his truck parked at the airport.

A search for a suspect at the Atlanta airport

Authorities say they began their search for Cagle after his family alerted the Cartersville Police Department that he had commented during a livestream that he was headed to the Atlanta airport to "shoot it up."

Cagle arrived at Hartsfield-Jackson Atlanta International Airport in a Chevrolet pickup truck that was parked outside the doors to the South Terminal. When police went to the vehicle, they found an AR-15 with 27 rounds of ammunition, Schierbaum said.

Less than half an hour after Cagle arrived at the airport, two Atlanta police officers approached him and asked him questions before taking him into custody. Cagle is heard screaming on one of the officers' body camera footage as they took him to the ground and put handcuffs on him.

Officer Myesha Banks has been serving with the Atlanta Police Department at Hartsfield-Jackson for over two years. She credited her training with making the situation go as smoothly and as quickly as she said it could.

"I did go into tunnel vision and all of my skills and everything I learned just came as one, and that's when I just went into straight police mode," Banks said.

She said that as soon as she was able to put a hand on Cagle's back, she knew that what could have been a serious situation had been mitigated.

"I felt something shift. I felt that whatever he had in his mind to do, I was going to stop it," Banks said.

A possibly deadly incident averted

Police estimate that more than 20 people could have been killed if officers hadn't been alerted in time.

On Tuesday, Mayor Dickens released a statement saying, "Yesterday reminded us how quickly things can change and how much it takes all of us to build one safe city. In one part of Atlanta, a young officer was seriously injured while responding to a call. Across the city, at the world's busiest airport, a potential mass shooting was prevented thanks to quick action and community vigilance."

Schierbaum commended Cagle's family, saying their swift action to say something to the police was the right thing to do.

"They saved lives and they saved their family member's life yesterday," he said.

Cagle was scheduled for a first appearance in Clayton County court on Tuesday morning, but that appearance has been postponed until Wednesday.