Passenger with box cutters on Frontier Airlines flight stopped by veterans, former officer

A passenger on a Frontier Airlines flight who allegedly boarded the plane with two box cutters and was seen acting erratically was taken into custody after an emergency landing Friday night, according to the airline and the Transportation Security Administration.

Several passengers on the flight, including military veterans and a former law enforcement officer, helped crew members subdue the man after they landed, according to eyewitnesses.

The flight was en route to Tampa from the Cincinnati/Northern Kentucky International Airport when it was diverted to Atlanta "after a passenger on board the aircraft was observed in possession of a box cutter," Frontier said in a statement.

ABC News spoke to Larry Cumberbatch, who was a passenger onboard Frontier Airlines Flight 1761 and is a Navy veteran.

Cumberbatch said two other men, another veteran and a former law enforcement member, worked with the crew of the plane to help detain the armed passenger and protect the other passengers.

About 45 minutes into the flight, Cumberbatch said flight attendants approached the three of them and asked for assistance with a passenger in the back of the plane.

At least two passengers said they saw some sort of blade from a man who multiple people noticed was acting erratically.

Cumberbatch volunteered to switch seats with the woman originally next to the armed passenger.

"They were concerned about a young lady, and they asked if anyone's willing to switch seats or maybe go back and sit back with him. So she could be safe. The situation was, the lady mentioned that the gentleman next to her had some kind of knife or weapon and he actually showed it to her," Cumberbatch said.

He then walked to the back of the plane, finding the armed passenger taking up the middle and aisle seat and boxing in the man seated in the window.

The erratic passenger seemed paranoid, as if someone was following him, but was not displaying the blade. He eventually moved to the bathroom while Cumberbatch stood in the aisle.

"His feet were up in the aisle seat. So, he just leaned back, relaxing. And I came and I said, 'I'm going to be sitting here right now.' You know, this is my seat. And he said, 'Well, no. That's the young lady's seat.' I said, 'Not anymore,'" Cumberbatch said. "I just stood there. And I think it made him... I don't know if he thought I was an air marshal or somebody. He got up and went to the rear, maybe to the restroom. And I continued standing at that point just because I wasn't I didn't want anyone with a knife behind me."

When the armed passenger exited the bathroom, he confronted Cumberbatch in the aisle, in what he described as a showdown.

"He basically stood by the bathroom door looking at me, fidgeting with, you know, his clothing. Maybe kind of pacing back a little bit, but not really because of not a confined space. He was trying to size me up to figure out who I was, and I just literally just play nonchalant," Cumberbatch explained. "So, I said, let me just let him know physically I'm there without having to stare at him, because that's going to antagonize, antagonize someone. I just want to, you know, de-escalate so we land."

The armed passenger eventually took a seat in the back of the plane for landing. The passengers exited the plane, leaving the crew, the two veterans, the former law enforcement member, and the armed passenger. The former law enforcement member attempted to walk the armed passenger down the aisle while the two veterans flanked him. Law enforcement was nearby, but not immediately visible.

"You could see the energy ramping up where uncertainty, the uncertainty of what's going to happen with this young man," Cumberbatch said.

The armed passenger reportedly made some kind of erratic move, triggering the former law enforcement member to tackle him. Law enforcement then arrested him.

Cumberbatch cited his military training, and his experiences growing up and riding the subway in 90s New York, where he saw box cutters as a weapon of choice, as preparation for the situation.

"Going through boot camp and the Navy kind of changed my whole perspective on how to serve other people and having a sacrificial mindset," he said. "But I knew I knew how to de-escalate situations as well, just because of different scenarios in my life. But honestly, him having a weapon, it didn't really faze me. I don't know. I can't explain it, but I just knew I could handle it. And if I didn't... well, I knew I could have. I didn't have any doubts about that."

Cumberbatch said he wasn't surprised the other two veterans stood up too.

"I think it came on the heels of understanding what happened in our past, a history with 911, and so forth. And I think that was in the forefront of my mind when I went back, because I was literally in the Navy the year I joined, before 911 happened," he said. "And when I heard that, that was the first thing I said, 'That's not going to happen again.'"

Cumberbatch noted that there were children on the plane, and in particular in the back of the plane where the armed passenger was seated.

Cumberbatch expressed that the flight crew acted responsibly and competently throughout the entire situation.

"I mean, they were very brave. They were talking to him, trying to assess, does he really have a weapon?" Cumberbatch told ABC. "(They were trying to see) what's going on with him mentally."

"The aircraft landed safely in Atlanta and the passenger in question was taken into custody by Atlanta law enforcement," De La Cruz said.

No details were available on the circumstances leading up to the discovery of the box cutter, and the person in custody has not been identified.

There were no injuries to passengers or crew members, according to the airline.

All passengers have deplaned and were being provided with overnight hotel accommodations in Atlanta. A new flight has been scheduled for Saturday morning to take the passengers from Atlanta to their final destination of Tampa.

Frontier Airlines sent ABC the following statement:

"Frontier Airlines flight 1761, which departed Cincinnati/Northern Kentucky International Airport earlier (Friday) evening en route to Tampa, diverted to Atlanta after a passenger on board the aircraft was observed in possession of a box cutter. No injuries to passengers or crew have been reported. The aircraft landed safely in Atlanta and the passenger in question was taken into custody by Atlanta law enforcement. All passengers have deplaned the aircraft and are being provided overnight hotel accommodations in Atlanta. A new flight has been scheduled for (Saturday) morning to transport passengers from Atlanta to their final destination of Tampa."

The CNN Wire contributed to this report.