(CNN) — A Frontier Airlines passenger necessitated an emergency landing and was later taken into custody Friday night after he was found with a box cutter, according to an airline spokesperson.
A second box cutter was later found in the passenger's carry-on luggage, the Transportation Security Administration (TSA) told CNN on Saturday afternoon.
Frontier Airlines Flight 1761 from Cincinnati to Tampa was diverted to Atlanta after the passenger was seen with the box cutter, spokesperson Jennifer De La Cruz told CNN in a statement.
"The aircraft landed safely in Atlanta and the passenger in question was taken into custody by Atlanta law enforcement," De La Cruz said.
There were no injuries to passengers or crew members, according to the airline.
All passengers left the plane and were provided overnight hotel accommodations in Atlanta. A new flight was scheduled for Saturday morning to take them to Tampa.
Agents failed to follow protocol, TSA says
The TSA said in a statement on Sunday it reviewed Friday's incident and found its security checkpoint agents at Cincinnati/Northern Kentucky International Airport failed to adhere to protocol when they discovered a box cutter in the man's carry-on luggage, which later caused the diversion when he allegedly threatened passengers mid-flight.
The person in custody, who has not yet been identified, went through the physical screening after presenting agents with a temporary Ohio driver's license. The traveler was carrying two backpacks and additional loose items through security, the TSA said.
The agency said the agents did not fully use the technology at their disposal, which would have identified the box cutters inside the man's carry-on luggage, nor did they follow protocol when they returned the removable "visible blades" back to the passenger after an inspection.
The man's luggage was scanned "using CT technology," which the TSA says creates a 3-D image that can be rotated 360 degrees for further inspection.
"Following review of the incident, including closed-circuit television (CCTV), the image review capabilities of the CT were not fully used," the agency said.
"The box cutters were not identified by the CT operator, but his property was identified for a further search. During the search, one box cutter was discovered. The visible blades were removed from the box cutter and provided back to the passenger," TSA's statement continued.
This is contrary to the standard operating procedure, according to the TSA, which requires that blades be placed in checked bags or "voluntarily abandoned."
The man's backpack, containing the other box cutter and the rest of the man's property, was screened for explosives, but the box cutter was not discovered at that time, TSA said.
The employees involved in the incident have been placed in a "training status" for remediation on CT image review and search procedures, according to the statement.
The agency said it will conduct "shift briefs" on the incident for all Cincinnati/Northern Kentucky International Airport and State of Kentucky employees, as well as schedule national and statewide trainings on technology tools and prohibited items.
Passenger alerted flight crew to risk
Lillian Hoffman, who was on board the plane, told CNN affiliate WLWT that she alerted the flight crew to the armed man after being made aware of him by another passenger.
"So, I went up and talked to the flight attendants at the front of the airplane and let them know like this guy has a box knife, and he's been telling us that he wants to stab people," Hoffman said.
The US Attorney's Office has taken the lead on investigating the situation, according to the TSA.
"TSA has started an internal review of the incident by viewing CCTV, airport security checkpoint processes/operations and will continue to provide updates as they are available. TSA can confirm that blades are prohibited in the cabin, but allowed in checked luggage," according to the statement on Saturday.
The Atlanta Police Department directed all questions about the incident to the FBI when contacted by CNN.