This was obviously a few years back, but from my understanding it happened...
There was a drug ring in a major city of China...
The authorities initially didn't do anything...or so it seemed. They just sat back watching and gathering evidence for about a year.
They got their spies inside and listed names and whatever else of those involved.
After about a year it came down to the final crackdown. All they did was go around kicking in doors and dragging people out of wherever they happened to be at that time. It was literally a couple of thousand people.
About half were sentenced to labor camp.
The other half (after about a half hour trial, in some cases in groups) were sent to a stadium where they (several hundred) were all executed all in one day.
The saying on the street in China is that there is no such thing as a repeat offender.