Hong Kong police made their first arrests under a new national security law imposed by China’s central government, arresting at least two protesters Wednesday for carrying flags and signs calling for Hong Kong’s independence.

In total, 180 protesters were arrested, seven under the new security law.

A man who had a Hong Kong independence flag was arrested at a protest in the city’s Causeway Bay shopping district after police had issued multiple warnings to the crowd that they might be in violation of the law, according to a police statement on Twitter.