NEW YORK — An Associated Press investigation has documented 345 instances in which people hopped over, crawled under, drove cars through or otherwise breached the fences and gates protecting the perimeters of 31 of the nation’s busiest airports between January 2004 and mid-February.

Here’s a look at some of those bizarre breaches, as described by airports or documents from the U.S. Transportation Security Administration.

WOULD-BE JFK STOWAWAY: In June 2015, a 17-year-old jumped a fence and was caught near an area where planes load at New York’s John F. Kennedy International Airport. He asked one airport employee who stopped him if he could take a selfie. The boy told police he wanted to stow away in an airplane flying to Morocco, his home.

HAILING A PLANE IN SAN FRANCISCO: In March 2015, a 42-year-old woman walked around a vehicle exit gate at San Francisco International Airport, and reached a cargo building where people in the air traffic control tower saw her waving her arms in an attempt to stop a plane. She later told authorities that she planned to stow away on a flight to Guatemala, to see her husband and child, much like a teenager who survived a flight from California to Hawaii in 2014. AP counted this as a perimeter security breach, though officials with the airport and the TSA insisted it was not.

GUN AT HEAD IN PHILLY: In April 2012, a woman who had just tried to steal a truck carrying $1 million worth of Jack Daniels whiskey got through a perimeter gate at Philadelphia International Airport and boarded a small jet. She was able to grab the gun of a responding officer, pointing it at his head with her finger on the trigger before he disarmed her. The gate guard’s boss was disciplined because the guard was not paying attention.

MISSING INTRUDER IN NEW YORK CITY: In December 2015, a worker at JFK asked a man walking near where aircraft are loaded and unloaded if he had an ID badge. The man said he was looking for the subway, warned the worker with an expletive not to report him and walked off across an airplane taxiway. Responding officers looked for the man near Terminal 8, but did not find him.

A 7-MINUTE DELAY: In July 2015, a man scaled two perimeter fences and ran onto a San Diego International Airport runway, halting inbound and outbound planes for 7 minutes before he was arrested.

ARMED WITH KNIVES: In February 2015, a man in a hoodie jumped a perimeter fence and was arrested near a gate after crossing the airfield at Minneapolis-St. Paul International Airport. Authorities found a knife on him. In March 2011 at Seattle-Tacoma International Airport, a man carrying a backpack with two steak knives jumped a fence and was stopped near a passenger gate.

NOT LEAVING LAS VEGAS: In April 2009, a man who appeared to be intoxicated climbed over a gate topped with barbed wire at McCarran International Airport, climbed into a helicopter and began preparing for a flight before the helicopter owner confronted him. He was arrested for criminal trespassing. Federal prosecutors declined to take the case.

TRACTOR HITS JET: In January 2007, a man climbed over a fence at the Las Vegas airport then stole a tractor, crashed it through a security gate, hit a corporate jet and then, as authorities chased him, drove into a ditch. He was injured when the tractor rolled.

LOS ANGELES LADDER CLIMBER: In February 2015, a man approached a Korean Airlines employee at Los Angeles International Airport and said his wife was in the car and they were looking for their way out. He got over the fence by taking a ladder that an employee was using on the outside to set up better lighting at a cargo facility.