KANSAS CITY, Missouri - Federal officials insisted Wednesday that screeners at Kansas City International Airport were just doing their jobs when they frisked a baby, an incident that gained worldwide attention after a pastor posted a mobile phone picture of the pat-down on Twitter.

The baby's stroller set off an alert of possible traces of explosives Saturday, so the screeners were justified in taking a closer look at the boy cradled in his mother's arms, said Nick Kimball, a spokesman for the Transportation Security Administration.

The Rev. Jacob Jester, an evangelist who snapped the photo Saturday after he cleared security for a flight to Albuquerque, New Mexico, said it didn't sit right with him to see the baby being patted down. He said he thought the boy was about 8 months old.

After taking the picture, he posted it on the social networking site Twitter, commenting that the search was "extreme." His wife and another pastor also posted it, and soon it was a cyberspace hit with more than 300,000 viewers. It eventually made it onto such websites as The Drudge Report and London Daily Mail, sparking complaints from many readers that the TSA's actions crossed the line.

"That was definitely a surprise," Jester said of the reaction to the photo. "I didn't expect to get all the attention I've garnered from that picture."

He said the woman whose baby was patted down contacted him later, and he apologized profusely for drawing all of the attention to her and her child.

"I apologized left and right," he said. "I said, 'I regret that I tweeted the picture in the first place. But she was laughing the whole thing off."'

Jester, who has an 8-month-old son of his own, declined to disclose the woman's name or any contact information.

The Kansas City airport is one of 16 in the US that uses private-sector screeners, instead of government screeners provided by the TSA, Kimball said, but private screeners follow government guidelines.

"Less than 3 percent of all passengers get pat-downs at the checkpoint," Kimball said.

The hubbub surrounding the Kansas City incident is similar to a story last month about a 6-year-old girl who was patted down at an airport in New Orleans.

The girl's mother, Selena Drexel, said she asked why her daughter was selected for a pat-down, but was not given a reason. Drexel and her husband uploaded the video of the screening onto YouTube, generating huge interest and prompting sharp criticism from a congressman involved in security issues.