A newly paroled man breached airport security Tuesday, boarding a commuter flight at the San Diego International Airport before he was arrested, launching an investigation from the U.S. Transportation Security Administration, according to an article from Reuters.

This event comes mere weeks after Minnesota Representative Chip Cravaack declared that the next 9/11-like attack will not pass through airport security, but come from the ground.

According to the Reuters article, the would-be stowaway, Marc Rory Duncan, 38, walked through an unlocked emergency exit onto the tarmac and onto the airplane with 27 passengers bound for Los Angeles, some 130 miles away.

The opened door set off an alarm, but by the time police and security personnel had responded, Duncan had already blended in with the rest of the passengers boarding the plane, the article says.

The flight crew noticed that they had one passenger too many, and Duncan gave up on his own, walking himself off the plane, the article says.

Duncan, who was unarmed and had not purchased a ticket, was arrested, and the TSA and Harbor Police inspected the plane with a canine team. All passengers had to rescreened, the article says.

San Diego Harbor Police Department Lieutenant James Jordan told Reuters that Duncan had been released from jail the night before after serving time for theft.

The TSA said in a statement Wednesday confirming the incident and subsequent investigation that “as is the case with any incident of non-compliance with security protocol, TSA has initiated an investigation and if necessary, will take appropriate action.”