WATCH: Huge Anti-Marriage Equality Rally Turns Violent

A massive protest in France by opponents of the country's new marriage equality law and rights for same-sex couples to adopt turned violent on Sunday.

Police in plain clothes were photographed in violent confrontations and dragging away protesters. Some posed bloody for the cameras. In the photo above, the protest is consumed in a cloud of tear gas. In other areas, riot police lined up in full gear with shields ready to turn back the melee.

Tens of thousands of people had gathered mostly peacefully earlier in the day. But as can be seen in the video below, that didn't last.