The horrific crime has rocked Latin America's largest nation and brought to fore the problem of violence against women in the country.
The police made the announcement after acting President Michel Temer called an emergency meeting of the security ministers for each state of the country to counter crimes against women.
"It's absurd that in the 21st century we have to live with barbarous crimes like this," Temer said in a statement. He added that the government would soon create a federal police force to check crimes against women.
The news of the assault grabbed headlines after several men joked about the attack online, posting graphic photos and videos of the unconscious, naked teen on Twitter.
Police have sought help from general public to track down the four men and identify the remaining culprits. Over 800 people had called a hotline that was set up to share information. The rape happened last Saturday when the girl had gone to spend a night with her boyfriend in the Sao Joao shantytown on the west side of Rio de Janeiro.
"I want them to await the justice of God. I feel like trash," the 16-year-old said in brief comments to O Globo newspaper. "It's the stigma that hurts me the most. It is as if people are saying 'it's her fault. She was using scanty clothes. I want people to know that it is not the woman's fault. You can't blame a robbery victim, for being robbed."
Addressing a press conference, police said the girl was allegedly raped by 33 men.