Brazilian police are in pursuit of over 30 men suspected of gang-raping a 16-year-old over the weekend in Rio de Janeiro, according to reports Thursday. The suspects posted a video of the assault on social media, triggering uproar in the country.

The victim was allegedly raped by armed men last Saturday while visiting a shantytown in western Rio de Janeiro, local police told the Associated Press. Other reports said that the girl was visiting her boyfriend’s house in the area when the assault happened.

Police have issued arrest warrants for the suspects, including the boyfriend, the BBC reported. The attack set off an online campaign against what activists call a rape culture in the South American nation, the report added.

According to the girl’s statement to police, she woke up last Sunday, naked and injured, and headed home. Days later, she found that some of the alleged rapists had posted pictures of the assault on Twitter. A 40-second video showing the assault was widely shared, followed by misogynistic comments, the BBC reported, adding that the accounts of the users were suspended. Speaking to local media, the girl's grandmother said the family watched the video and cried.

“I regretted watching it. When we heard the story we didn’t believe what was happening. It’s a great affliction. It’s a depressing situation,” the girl’s grandmother told Folha de S.Paulo newspaper, according to the BBC. “She is not well. She is very confused. This was very serious.”

Campaigners have reportedly called for protests over the coming days against the assault.