Karen Klein has yet to receive apologies from the middle schoolers who had verbally assaulted her Monday on board a Greece bus, she told CNN's Anderson Cooper.

Klein has received overwhelming expressions of sympathies in social networks after a video clip of the bus bullying has gone viral since Wednesday.

"I'm so amazed," she told People. "I've gotten the nicest letters, emails, Facebook messages. It's like, wow - there's a whole world out there I didn't know."

Love for Karen Klein

Concerned citizen "Max S" had set up a fundraiser dubbed "Love for Karen Klein" for the 68-year-old bus monitor to allow her to go on a vacation following the horrific ordeal. A total of $US275,000 ($A270,922) has been raised as of Friday morning.

Southwest Airlines had offered Karen and nine of her friends an all-expense-paid vacation to Disneyland in California.

Apologies via CNN

Despite all the reactions raised on the viral video, Klein has yet to receive any apologies from the middle schoolers who had insulted her. Two of them, however, sent apologies via CNN.

A student named Josh had written he is sorry and he could not believe he took part on the verbal assault against Klein.

"I feel really bad... I wish I had never done those things. If that had happened to someone in my family, like my mother or grandmother, I would be really mad at the people who did that to them," wrote another student named Wesley.

Asked whether she accepts the apologies, Klein said:

"I haven't gotten any yet. One is supposed to be being mailed but I haven't gotten that one so the other two -- I might not get anything from them anyway."

Klein's message to the middle schoolers' parents

Responding to People's query on her message to the parents of the middle schoolers who verbally assaulted her, Klein said:

"I'm sorry that your sons acted the way they did," she said. "I'm sure they don't act that way at home, but you never know what they're going to do when they're out of the house."

Klein recalls ordeal on the bus

"I tried to ignore it...I didn't hear some stuff and tried to shut them out," Klein told 13WHAM's Patrice Walsh.

While Klein did not hear everything, she recalled one of the kids taunting she "didn't have a family because they all killed themselves because they didn't want to be near you."

Walsh later reported Klein's oldest son died of suicide a decade ago.

Bullying consequences

When Cooper asked her what she wanted to happen to the kids as punishment, Klein said:

"I want them to make sure they never do this again to anybody. I would like them to be kept off the bus for a year and forbidden to play any sports at least for a year."

Meanwhile, Greece Police confirmed the families of the kids on the video are suffering consequences of the bullying.

"Their families have been threatened. We have custody of one of their mobile phones, and he had over 1000 missed calls and 1000 text messages threatening him. And he's 13 years old. That must stop," Greece Police Captain Steve Chatterton said on Thursday.

RELATED STORIES