KANSAS CITY, Mo. — Security agents detained a man and shut down one of three terminals at the main airport in Kansas City after detecting suspicious items inside his carry-on bag on the 10th anniversary of the Sept. 11 terrorist attacks.

The man was stopped about 9:30 a.m. today at the Southwest Airlines checkpoint at Kansas City International Airport. Transportation security agents who detected suspicious items in his bag asked to examine them, and he was detained when he refused, airline and law enforcement officials said.

A bomb squad was called, the area around the checkpoint evacuated and the terminal shutdown, they said.

One of the suspicious items has been cleared by explosives experts at the airport and another was being investigated, according to a homeland security official who spoke to The Associated Press on condition of anonymity to discuss an ongoing investigation. The FBI is investigating.

FBI spokeswoman Bridget Patton said a suspicious package was X-rayed and no explosive material was found. She declined to say what was in the bag, but said the package was “disrupted in such a way to preserve” evidence by the bomb squad. The man is the custody of airport security, she said.

TSA released a statement confirming the area around the checkpoint was evacuated “out of an abundance of caution.” Several TSA officials did not respond to calls requesting more details.

Laura Brown, spokeswoman for the Federal Aviation Administration, referred questions to the TSA.

Early indications were that the incident did not appear to be connected to terrorism, but the investigation was continuing and there had been no official determination, according to a law enforcement official speaking on condition of anonymity to discuss the ongoing probe.

Airport spokesman Joe McBride said the airport had heightened security since Thursday because of the 10-year anniversary of the Sept. 11 attacks but there was no known threat involving the airport.

He described the customer as “belligerent” and said he had multiple carry-on bags.

The entrance to the parking lot for the terminal where Southwest is located was closed this afternoon and passengers were being told to park elsewhere. Some flights were still going out of the terminal, but many passengers at the busy airport were being rerouted.

Other than delays caused by closing the checkpoint for a few hours, no flights were affected, Southwest spokesman Chris Mainz said.