Hong Kong police used a sweeping national security law Thursday to arrest five editors and executives of a pro-democracy newspaper on charges of colluding with foreign powers, the first time the legislation has been used against the press in yet another sign of an intensifying crackdown by Chinese authorities in the city long known for its freedoms.

Police said they had evidence that more than 30 articles published by Apple Daily played a ‘crucial part’ in what they called a conspiracy with foreign countries to impose sanctions against China and Hong Kong.