ATLANTA (AP) — In a swift response to a potential threat, federal prosecutors have charged a Georgia man who was apprehended at Atlanta’s international airport following a tip-off from his family. The incident unfolded when relatives reported his intentions to carry out a shooting at the bustling travel hub.

Authorities revealed that Billy Joe Cagle, 49, made a menacing declaration during a FaceTime call. While on the road, Cagle allegedly threatened to unleash violence at the world-renowned Hartsfield-Jackson Atlanta International Airport. The call ended ominously with his words, “I’m at the airport, and I’m gonna go rat-a-tat-tat,” according to the prosecutors’ statement.

Atlanta police acted quickly, apprehending Cagle on Monday at the busy airport. An alarming discovery followed as officers found an assault rifle and ammunition in his vehicle parked outside, as confirmed by Police Chief Darin Schierbaum.

Following Cagle’s arrest, federal charges were filed on Tuesday. He faces accusations of attempted violence at an international airport, making interstate threats, and possession of a firearm as a convicted felon.

The swift intervention started when Cagle’s family in Cartersville reached out to local police, who promptly contacted Atlanta authorities. Within a remarkable 15 minutes, officers at the airport located and arrested Cagle. Cartersville, the town where the incident was reported, is situated approximately 50 miles (80 kilometers) northwest of the airport.

“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,” U.S. Attorney Theodore Hertzberg said in the statement.

Online jail records showed that Cagle was being held in the Clayton County Jail on state charges of possession of a firearm by a felon and terroristic threats. Schierbaum said Tuesday that he would be transferred to federal custody.

It was not immediately clear whether the man had a lawyer who could comment on his charges and attempts to reach his family were unsuccessful.

Sgt. T. Jones, who has about six months left in her three-decade career with the Atlanta Police Department, was on the phone with one of Cagle’s family members Monday morning, relaying information to officers to help them identify him. She and other officers spoke about the arrest during a news conference Tuesday.

“This is what I’ve trained to do and I’ve loved doing this for the past 29 years and it’s just an amazing feeling,” she said of helping to avert a potential tragedy.

Officer M. Banks, who has been with the Atlanta Police Department for nearly three years and at the airport for about two years, identified and arrested Cagle.

“I was scared. It was fearful for a second,” she said of the moment she approached him, adding that her training kicked in, but that she was fully aware of how easily things can go wrong.

Nick Roberts, who has known Cagle since high school, texted his friend Sunday night after being concerned by Facebook posts he had made. He said Cagle was struggling with mental health issues. Cagle had posted on Facebook earlier Sunday that he is schizophrenic and was taking medication.

Roberts said Cagle called him at about 9 p.m. Sunday night and assured him he was OK. Roberts said Cagle loved his two daughters and worked hard hauling hay and doing fencing work.

“I want folks to know that he wasn’t some monster,” Roberts said. “This was a very big surprise for a lot of us that went to high school with him and know him in the community.”

During a news conference Monday, police showed surveillance video that they said showed Cagle arriving at the airport and body-camera video of his arrest.

A Chevrolet flatbed pickup truck is seen arriving curbside at the airport terminal around 9:30 a.m. and then a man police identified as Cagle is seen entering the airport a few minutes later. He walks over to the TSA security checkpoint and had “high interest in that area,” Schierbaum said.

Body-camera footage shows Atlanta police officers, who had a photo of Cagle provided by his family on their phones, approach him and begin asking him questions before taking him into custody. As they take him to the ground and put handcuffs on him, Cagle can be heard yelling.

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Associated Press reporter Hallie Golden in Seattle contributed to this report.