(CNN) - A woman hurled a shoe at Hillary Clinton on Thursday during a speech in Las Vegas, according to the Secret Service.
She ducked and it missed her, joking afterward about the incident that occurred during an appearance before a recycling trade group.
"My goodness, I didn't know solid waste management was so controversial," she quipped.
"Thank goodness she didn't play softball like I did," she added.
The Secret Service took the woman into custody. They said she was not a ticketed guest and slipped past hotel security.
She was not named and only identified as a protester. But it was not clear what she was protesting.
The incident happened shortly after Clinton took the stage to address the meeting at the Mandalay Bay hotel-casino.
Mark Carpenter, spokesman for The Institute of Scrap Recycling Industries, said the woman was not affiliated with his group and was not credentialed for the event.
He said she "must have slipped under the rope at the last second."
"I saw papers fly when the protester stood up. I saw papers flying in the air," he said.
Carpenter said there were about 1,000 people in attendance.
Clinton's appearance is the latest in a series of high-profile speaking engagements for the former secretary of state since leaving the Obama administration. She is considered the overwhelming favorite for the Democratic nomination in the 2016 presidential race.
CNN's Dan Merica contributed to this report.