Police said Friday that they have identified and are searching for four of the more than 30 men suspected in the gang rape of a 16-year-old girl. The rape case has rocked Latin America's largest nation and highlighted its endemic problem of violence against women. Authorities say the rape happened last Saturday while the girl was visiting her boyfriend in a shantytown on the west side of Rio de Janeiro. Arrest warrants have been issued, including one for the boyfriend. The assault has provoked an online campaign against what campaigners call a culture of rape in Brazil. A 40-second-video was widely shared and followed by a wave of misogynistic comments, before the users' accounts were suspended.