you need to know the whole chain of events to understand what happened at Yuen Long last night. also you need to know the unique identity of Yuen Long in order to comprehend the situation. Yuen Long is a village of people from several big family names, they are all relatives in a way. have their own system and rules and really hate outsiders telling them what to do. in history, they fought with British, fought with Japanese, with government, HK government and Police then realize the best way is to allowing local'daddies'to run local affairs with minimum intervene,except serious crimes like rape, murders, drugs etc. Protesters dont get this, last week, they entered Yuen Long enforcing 'democracy', got told off and kicked out. Local warned, they dont want protesters in their area, if they come back ,YL locals will teach them a lesson about not to invade into others' community. but protesters took it as a challenge to their righteousness and claim they will 'liberal' Yuen Long. Locals got super irritated and with gang history of this area, they are not afraid of confronting with anyone,violently or not. so, they did it as they have always done when outsiders disrespect them. local police did not stand by protesters. but take what happened during last few weeks, like an officer got a finger bitten off but then was criticized 'excessive violence'etc. of course police have their own emotions, they are human beings after all, not robots. anyway, this is a tragic situation which is inevitable to happen , not after so many weeks of tolerance of violence and breaking law. the protesters once shouted at police asking them to disappear. and police disappeared. you call for lawlessness, then you have to live with lawlessness. you dont want to get punished by beating others, then you have to live with being beaten without anyone punished.