The demonstration to Yeouido started with at least 800 people. More in Korean you can read here. The end of the story - "The Battle" - you can read/see tonight.

In the afternoon...

...at about 4:30 pm the demo started

But just after 100 Meters...

...the riot cops started the first...

...attack

Blocking the cops leading car

...

Police state!

Defending the demo route