About 1,000 people held a march on Saturday to remember the victims of the Itaewon crowd crush, including 150 family members of those who died in the tragedy some 100 days ago. But clashes with squads of police officers marred the somber event as authorities attempted to stop participants from erecting an unapproved altar in front of City Hall.

The mourners initially planned to hold the event at nearby Gwanghwamun Square and to set up the memorial altar there. But the Seoul municipal government rejected the requests, and the police agency dispatched about 3,000 officers to ensure mourners couldn’t access the area.