ATLANTA (AP) — Police arrested a man at Atlanta’s bustling airport on Monday after getting a tip from his family that he was planning to shoot up the place, and found an assault rifle and ammunition in his truck outside, the city’s police chief said.

Billy Joe Cagle, of Cartersville, Georgia, had described his plan to shoot up the world’s busiest airport on a social media livestream, Chief Darin Schierbaum said during a news conference.

“The Cartersville Police Department was alerted by the family of Mr. Cagle that he was streaming on social media that he was headed to the Atlanta airport, in their words, to ‘shoot it up,’ and the family stated that he was in possession of an assault rifle,” Schierbaum said, describing Cagle as a “convicted felon.”

Cagle, 49, arrived at Hartsfield-Jackson Atlanta International Airport in a Chevrolet pickup truck that was parked right outside the doors to the airport terminal. When police went to the vehicle, they found an AR-15 with 27 rounds of ammunition, Schierbaum said.

Cartersville police Capt. Greg Sparacio, whose department received the initial tip from family members, said Cagle “had the intention to inflict harm to as many people as he could.”

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