The evidence of police:

When journalists observed at the police’s line of defence, it was found out that only a few riot police officers were showing their police IDs on their uniforms, which many of them decided not to show their warrant cards or Police IDs. There were police officers put a paper written ‘ATOM’ instead of warrant cards in their vest’s pockets near their chests. Apart from helmets, the riot police officers even wore goggles. The atmosphere was very tense.

Source:

HK01