It goes often like this.
1. Censoring. They cordon-off with specially trained police.
Any incident, disaster, protest etc., the first reaction by the party security apparatus is not to let it be seen.
This includes completely erasing the people, places, artifacts from the internet. Not to allow it to be mentioned.
2. Blockage and arbitrary detention. Those involved in protests, riots etc. are blocked off. They are put in a room, and sometimes kept there for couple of months without any info. Their families, too, remain unaware of their whereabouts. No phone call. No lawyer. No charging with crime oftentimes.
3. Blackmailing. Relatives of those kept under arrest are threatened. The suspect is told not to repeat the offense, otherwise the relatives will be arrested, too.
Constant harassment by party gangs.
4. Complete surveillance. There is a reason why the party-land loves electronic payment and AI face detection. It empowers the regime. Gives a total control over people's movements, financial and personal.
5. And many security-crazy stuff: They make you drink from your bottle if you want to enter the metro with a water in hand. Every place has detection and security. All places, homes and offices are barred and guarded. In many places, knives in restaurants are chained to the work table.
And many more measures to terrorize, frighten and subdue regular people. Because, it is of the party, by the party, for the party.