No charges were immediately announced, but the FBI said Friday in a statement it had "located and interviewed an individual believed responsible" for the action, which other government officials said appeared intended to demonstrate gaps in aviation security.
The person was not officially identified. But a congressional official and two senior law enforcement officials, all speaking on condition of anonymity, said the perpetrator was a 20-year-old male college student from North Carolina.
An FBI agent called officials at Guilford College in Greensboro, N.C., on Friday afternoon inquiring about a student in connection with the investigation, the Greensboro News & Record reported, quoting Randy Doss, vice president for enrollment and campus life.
"We had no reason to suspect that a student was engaged in this reported activity," Doss said in a statement. "We also have no reason to believe that any other Guilford students are involved in this situation or investigation."
The congressional official said the man, who was not arrested, had informed the Transportation Security Administration earlier that he planned to put packages on aircraft to make a point about aviation security.
CBS News Correspondent Bob Orr says sources tell him the planting of the box cutters was probably an "inside job" designed
to reveal vulnerabilities.
The FBI statement said further legal proceedings were expected in federal court in Baltimore. Officials would not reveal how the man was located so quickly and refused to give other details about the case, other than to say terrorism was not involved.
"It doesn't appear to be a terrorist event," FBI Director Robert Mueller said. "I think it is safe to fly."
The suspicious bags were hidden in lavatory compartments aboard Southwest Airlines jets that landed in New Orleans and Houston. They were found late Thursday by maintenance workers.
As a precaution, the government ordered intensified searches of the roughly 7,000 U.S. commercial aircraft. The checks were expected to be completed by late Saturday, with no disruptions to service.
Southwest said in a statement that the items appeared "intended to simulate a threat" and that each bag was accompanied by a note that "indicated the items were intended to challenge Transportation Security Administration checkpoint security procedures."
One law enforcement official said each note included precise information about where and when the items were placed on board the aircraft.
In addition to the box cutters and notes, the bags contained bleach, matches and modeling clay, according to the official. The bleach on one of the planes was in a suntan lotion bottle and in an unidentified container on the other plane.
The clay was formed to look like a plastic explosive, while the bleach could have been used to demonstrate how a corrosive or dangerous liquid could be smuggled aboard an aircraft.
Though government officials were quick to say there were no indications of terrorism, the discovery aboard the Southwest planes was a chilling reminder of the Sept. 11, 2001, attacks. The 19 hijackers used box cutters to take over four jets that day. Box cutters and bleach are now are among the items that cannot be carried onto planes.
The TSA was created after the attacks, with the goal of replacing privately hired airport security workers with better-trained and higher-paid government employees. Problems with screening passengers and bags have persisted, however. For example, officials say X-ray machines can't detect plastic explosives.
Southwest spokeswoman Beth Harbin said the New Orleans plane had originated in Orlando, Fla., and was scheduled to go on to San Diego later Thursday night. The crew reported a lavatory wasn't working and a maintenance worker discovered the bag while working on the problem at about 9 p.m., she said.
A short time later, a bag was found aboard the Houston aircraft, which had arrived from Austin, Texas, for routine maintenance. Southwest said security checks of its entire fleet of 385 aircraft found no other suspicious items.
All airlines conduct routine searches of their planes. Homeland Security Department spokesman Brian Roehrkasse said a government directive issued after the bags were found instructed carriers "to make sure the searches are done in a comprehensive and thorough manner."
Paul Rancatore, deputy chairman of the security committee for American Airlines' pilots union, described the routine searches as fairly perfunctory.
"It's kind of a walkthrough. They're just looking for things that are obvious," Rancatore said. "There's no removing of panels, no dogs."
Rep. John Mica, chairman of the House aviation subcommittee, said the incident demonstrates the need to screen all employees with access to aircraft and whatever they bring on a board. He also said TSA needs improved technology to screen for explosives and banned objects.
"We need to have TSA get its act together and put in place the adequate training and technology to deal with the threat," said Mica, R-Fla.