Johannesburg (CNN) -- South Africans woke up on Wednesday morning to the claim that a group of Soweto youths had filmed themselves raping a 17-year-old girl believed to be mentally ill.
The cellphone video is said to have gone viral among school kids in the township south of Johannesburg, and the term #rapevideo was trending on Twitter in South Africa on Wednesday.
The Daily Sun, a local tabloid, reports that it alerted the police after a concerned mother whose daughter was watching the video handed it over to the paper on Tuesday.
"The mother of a teenage girl saw the horrifying pictures and confiscated her daughter's phone. A work colleague of the woman said they recognized some of the boys and advised her to take the video to Daily Sun," the newspaper reported.
The suspects, aged between 14 and 20, were arrested Tuesday morning and charged with kidnapping and rape, police spokesperson Warrant Officer Kay Makhubela said.
"The video is very bad. The men can be clearly identified as they take turns raping and filming her," she told CNN.
The girl's mother reported her missing on March 21, Makhubela said.
Media reports suggest the police initially failed to open a missing persons case but that they have since done so.
Police suspect the girl was kidnapped and turned into a sex slave.
A local radio station got hold of the video and has been getting requests to post it.
On Twitter, Eyewitness News editor Katy Katopodis said the station would never do that.
"To those asking for the #rapevideo link that #EWN reported on today. Stop! Not happening! We'd never put it on our site. Illegal & wrong," she tweeted.
The distribution of pornographic material is illegal in South Africa.
The station reports that the gang of men promised the girl 25 cents for her silence.
"The girl can be heard pleading with the boys to stop. They crudely jest and crassly spur one another on," journalist Mandy Weiner reported.
NGOs estimate a woman is raped every 26 seconds in the country.
According to the latest police statistics more than 60,000 cases of sexual assault were reported in the year to March 2011, down from 70,000 in 2008.
A popular radio talk show host broke down Wednesday morning as she encouraged listeners to come up with solutions to the problem.
Women's rights activist Lisa Vetten says in the province of Gauteng, where Johannesburg is located, one in every five rapes is a gang rape.
"Rape is a young man's crime. It's a bit of a performance for them, showing off to each other how macho they are. We need to teach our young men that you can be masculine in ways that do not involve violence and degrading women," she said.
The government is well aware that the problem needs urgent attention, experts say.
"We are not lacking in terms of legal instruments to deal with this kind of thing. What we lack are ways of making these instruments effective," said Nomboniso Gasa, an expert on gender and culture.
The country has created a ministry of women and children precisely to deal with violence against women and other related matters.
Its minister Lulu Xingwana says this case will be be a high priority.
"I will speak to the minister of police to ensure that this case is prioritized. Distributing child porn is illegal in this country so the police must confiscate this video," she said in a radio interview.
The newspaper that broke the story says they were the ones that informed the victim's mother.
The tearful woman reportedly said her daughter had been a victim of rape since the age of 12.
"People took advantage of her illness and because my family is poor," the Sun quoted her as saying.
Police did not confirm her mental ability or allegations she had been raped before.