Beijing (CNN) Liu Lizhu was not aware her shy, 15-year-old son had been bullied at school until he ended up in hospital with a ruptured spleen.

On June 8, the night before his high school entrance exams, her son Huang Tanghong was beaten up by three bullies at his school in southeastern China's Fujian Province, who had routinely abused him in the past few years, his family members told CNN.

He lay curled up on the floor when the battering was over. He was too afraid to tell his parents and kept silent, his mother Liu later said.

The next day, he was in such acute pain that he was taken to hospital in the middle of an exam and doctors performed surgery. It was only then his classmates told Liu, a migrant worker who was working in another city, that he'd been bullied.

Some of Huang Tanghong's bruises and injuries are pictured.

"They beat him and tortured him just for the sake of it," she told CNN. "I'm of course livid and heartbroken; he's my flesh and blood."

Huang's experience received much public attention after his angry cousin took to social media to call for justice, posting graphic images of Huang's spleen and stitches.

The bullies were later taken into custody for causing serious injury, but were released soon after their parents agreed to pay Huang's family with 210,000 yuan ($33,000) in compensation, according to Liu.

Huang's school refused to reveal more details on the case when contacted by CNN.

Enough intervention?

Huang's plight and a string of similar case have sparked heated discussions, especially online, about the lack of legal protection for victims of bullying at schools.

Stories, videos and images of bullying -- some voyeuristic -- have been widely circulated and a hashtag on Weibo, China's version of Twitter, for anti-campus-violence has gained traction.

Under the current Child Protection Law in China, minors under the age of 16 do not face harsh punishment unless they commit serious crimes such as murder.

students were At least 30 serious bullying cases have been reported by Chinese media in the past nine months. Schools responded to most of these incidents by penalizing perpetrators with a mark on their school record. In the most extreme cases, the bulliedstudents were beaten to death

In July, China's Internet watchdog, the Cyberspace Administration of China, banned websites from posting "obscene or violent" videos involving child bullying "to protect juveniles' mental and physical health," the China Daily reported.

But in October, just after the start of the new school year, another video went viral. It showed four girls between the ages of 12 and 14 viciously striking another girl, including the lower parts of her body, for over three minutes.

According to a report in Chinese media , local authorities said the Department of Education and the public security bureau have investigated and verified the incident.

The violent outburst, authorities said, originated from a trivial quarrel between the girls from weeks before the attack.

Bullying epidemic: Whose problem is it?

Figures have suggested the problem is widespread -- as high as one in five students.

study published in 2012, which looked at four cities in the southern province of Guangdong, found that 21% of middle school students reported being involved in bullying -- as a perpetrator, victim, or both.

The last category of students, who both bullied others and were bullied themselves, are caught in a cycle of aggression and shame and are likely to face more serious health risks and problems, the report said.

It said several factors were associated with bullying -- including peer pressure, broken families, feelings of insecurity and increased time spent online. Family income, however, showed little correlation.

Photos: Making the grade in China Pressure in China's education system starts young. Although parents, teachers and lawmakers have questioned the wisdom of putting so much pressure on young children, there's little sign their study load has been reduced. Hide Caption 1 of 9 Photos: Making the grade in China In Hong Kong, where formal pre-school education begins at the age of three, many prospective parents begin mapping out education plans before their children are born. Hide Caption 2 of 9 Photos: Making the grade in China China's often tough approach to bringing up children was made world-famous by Amy Chua, the Chinese-American professor who expressed her expectations of top grades and musical excellence in her book "Battle Hymn of the Tiger Mother." Hide Caption 3 of 9 Photos: Making the grade in China Students in China commonly have to take extra-curricular classes or hire tutors after school. The ultimate goal is to do well in annual National College Entrance Exams -- or gaokao -- the only way to get into college. Hide Caption 4 of 9 Photos: Making the grade in China Almost 9.5 million high school students in China took the 2015 gaokao in early June. Failure potentially means no degree and poorer job prospects. In this picture, parents crowd a police car outside Maotanchang High School as students leave to sit the 2015 college entrance exam. Hide Caption 5 of 9 Photos: Making the grade in China The stakes are so high some students have stooped to ingenious methods of cheating. A police officer displays a device used by students to cheat in previous years. Hide Caption 6 of 9 Photos: Making the grade in China A Chinese student gets his belongings searched before he enters the room to take the tough college entrance exams or Gaokao, in east China's Anhui province on June 7, 2012. Hide Caption 7 of 9 Photos: Making the grade in China A record high of 7.5 million students graduated from college this year. However, the job market doesn't look very promising. Nearly 8% of last year's college graduates remained unemployed within six months after graduation, according to state news agency Xinhua. Hide Caption 8 of 9 Photos: Making the grade in China Yet the gaokao perhaps is not as important as it used to be, with more Chinese studying abroad. Some 460,000 Chinese studied abroad in 2014, according to China's Ministry of Education. The United States, Canada, the United Kingdom and Australia have seen a rapid growth of Chinese undergraduate population on university campuses in the last decade. Hide Caption 9 of 9

What can be done?

Liu Chaoying, a Beijing-based psychological counselor, said harsher punishments for bullies wouldn't address the underlying issue.

Of more use would be effective psychological counseling services for student at schools but many don't have the resources to offer this.

She said that many perpetrators and victims come from families where parents and children don't communicate openly. These children have not been able to develop healthier mechanisms to deal with and express negative emotions.

"Kids at this age may react to the smallest things with extremely brutal behavior and they don't necessarily understand the consequences of violence."

She calls for parents and educators to work together to address bullying in schools, since it reflects social problems at a deeper level. And it is important that parents step in, she added.

"Parents need to spend enough time with their children, and take seriously their responsibility as guardians to nurture them," she said.

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"They need to start from little things like learning what happened to their children at school that may have upset them, so that their negative emotions won't accumulate to the extent that they would turn to violence."

But many of the perpetrators and victims, including Huang, are part of China's "left behind generation" that barely see their parents.

One in five Chinese kids have one or both parents who are migrant workers -- working far from home in China's factory boomtowns.

They struggle at school, have higher rates of mental health issues, and suffer from more behavioral problems than their contemporaries.

An uncertain future for young victims

For Huang Tanghong, who was hospitalized halfway through his high school entrance exam and didn't pass as a result, his academic future remains uncertain.

It's unclear when -- or even whether -- he will retake the test and carry on with his education. He is now recovering at home. His mother has moved back home to take care of him.

Huang undergoes treatment at the hospital.

"How can I even think about work when my son is still sick," Liu said. "I have to take care of him around the clock."

The local authorities and the school didn't react to Huang's case until it garnered media attention, according to Huang's family members.

Huang's cousin, Huang Jiaxin, told CNN that the school's tardy response shows just how the institution fails to protect students, even on its premises.

"Small fights can slip under the radar," said the distressed cousin. "But when you need to remove an organ? That's serious."