Turkish riot police officers block access to Istikjlal avenue as LGBT rights activists try to gather for a parade, which was banned by the government, in Istanbul on June 25.

Organizers of the 2017 Istanbul LGBTI+ Pride had vowed to march in central Taksim Square, using a Turkish hashtag for "we march," despite the ban on gay pride observances ordered by the Istanbul governor's office for the third year in a row.

Police used tear gas to disperse the crowds and activists said plastic bullets were also used. Riot-control vehicles and buses were dispatched to the area. Turkey's official Anadolu news agency said "an estimated 20 people" were detained after protesters did not heed warnings to disperse because the march did not have a permit.

PHOTOS: Istanbul Police Enforce Ban on Pride Parade