The incident occurred in Greece, New York, near Rochester. Klein is a bus monitor for the Greece Central School District, and the harassers hail from a district middle school, the school said Thursday on its website, although it did not identify Klein.
Klein described her tormenters "regular, normal kids" and said that "one on one, they're OK."
"Just don't get a bunch of them together. That's when the trouble starts," she said.
As the intimidation unfolded, she said, she tried her best to disregard the harassment and didn't hear everything that was uttered. But she said the hazing hurt deeply. At one point, she said, she told two children, "I am a person, too. I shouldn't be treated this way."
Klein told WHAM that she doesn't know whether bullies can be charged. But, she said, "they should have some form of punishment."
Attempts to reach all parties involved Wednesday were unsuccessful.
The video prompted an outpouring of support and a fundraiser by an international crowd funding site that had gathered more than $200,000 Thursday afternoon.
"Let's give Karen a vacation of a lifetime. Let's show her the power of the internets and how kind and generous people can be," the fundraiser's organizer, identified as Max S., said on the indiegogo.com website. He notes that she earns about $15,000 a year as a bus monitor.
"Everyone at indiegogo was so proud this morning to see Karen Klein on television talking so bravely about her experience and we hope that this indiegogo campaign contributes positively to the important national discussion about bullying," indiegogo's CEO, Slava Rubin, said in a statement.
The organizer was joined Thursday by a woman identifying herself as Klein's daughter, Amanda.
"I have spoken with Max and with Indiegogo and we just want to thank you so much for your support," the woman wrote on the site. "We are completely overwhelmed."
The school district said its bullying team and the local police are conducting an investigation.
"We have discovered other similar videos on YouTube and are working to identify all of the students involved," the school district said in a statement.
It did not elaborate on whether the additional videos are related to Klein's case.
"While we cannot comment on specific student discipline, we can say that students found to be involved will face strong disciplinary action," the school district said.
The students are minors, according to the school district. CNN does not name minors involved in alleged crimes unless they are charged as adults.
Officials involved in the investigation will hold a news conference Thursday.
Klein said she hopes the spectacle "might help other people." And, she said, she hopes that these children "get their share of someone bullying them."
"I hope what goes around comes around," she said.
CNN's Stephanie Gallman and Darrell Calhoun contributed to this report.
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