Update: Read more in-depth coverage of this protest from Global Voices with many more photos here

Several ten thousands have gathered at Seoul Plaza (as of 3 pm) to protest against the South Korean government's election manipulation scandal and the latest clampdowns on labor groups. The numbers are rapidly growing and the protest will continue throughout the day. Aiming 1 million Koreans to participate in ‘the December 28th General Strike', a detailed schedule [ko] of a series of protests held by different groups in major cities across the country has been widely shared in South Korean online venues in last few days. 

The December 28 General Strike (and protest) against the fraudulent election is being held at the City Hall Plaza, now as of 3:22 pm. 

Actually it can't be said people are ‘in’ the Seoul Plaza. Even the nearby road s are packed with people.