(CNN) Protesters gathered outside the Libyan Embassy in central Paris following an exclusive CNN investigation into migrant auctions in Libya.

"We have to mobilize. We can't let this kind of thing happen," one protester told France 24 at the rally Saturday. "Did we really need to see such shocking pictures before taking a stand? I don't think so."

After obtaining footage of an auction, CNN's Nima Elbagir and her crew went to Libya in October to investigate further.

"How can it be that in the 21st century, we're selling human beings like merchandise?" one woman at the Paris protest said. "I cannot get my head around that!"

Libyan authorities this week launched a formal investigation into the auctions, overseen by the government's Anti-Illegal Immigration Agency.

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