(CNN) A security incident Monday at New York's John F. Kennedy International Airport set off different explanations from federal and local authorities.
Eleven people went through an unattended Transportation Security Administration security checkpoint at the airport around 6 a.m. Monday, the Port Authority of New York and New Jersey said.
The TSA alerted the Port Authority about the lapse roughly two hours later, according to Joe Pentangelo, senior police public information officer at the Port Authority. By that time though, authorities could not find the 11 people as the "travelers in question boarded various flights," Pentangelo said in a statement.
Port Authority police identified three of the passengers who went through the unattended TSA PreCheck security checkpoint through video and sought to identify the remaining eight.
Meanwhile, the TSA called the incident a "possible security incident" and said it had affected just three passengers.
Of the 11 people walking through the unattended checkpoint, three set off the metal detector, TSA spokesman Nico Melendez said Tuesday.
"Those are the three we located in San Francisco when they landed," Melendez said. "We didn't need to find the other eight because they had been screened by canine and didn't alarm, so no need for further screening."
A TSA official had said earlier it was determined that the measures taken concerning the three passengers were "all that was necessary."
"TSA works with a network of security layers both seen and unseen. We are confident this incident presents minimal risk to the aviation transportation system," the agency said Monday.
The TSA said it would "take appropriate action" once a review was complete.
Nevertheless, the incident alarmed some travelers at JFK.
"We rely on that to make sure our flight is safe, to make sure everyone on there is not a danger, doesn't pose any danger and we can fly safely," Marianna Iannotta told CNN New York affiliate WCBS-TV regarding airport security screening. "So that's a little scary."
The TSA has grappled with security breaches before.
On Saturday, a man forced his way through the exit lane of the security checkpoint at Honolulu International Airport, where he was described as being "combative." He later died after being detained, the Hawaii Department of Transportation said.
Others have slipped past security in a less conspicuous manner.
In 2015, a Texas man without a ticket walked past security checkpoints without the TSA stopping him, according to The Dallas Morning News. In 2014, a woman known for her repeated attempts to board planes without tickets, slipped through the security checkpoint at Mineta San Jose International Airport to board a flight to Los Angeles, authorities said.