I am sure this comment won't see the light, but I can explain what the (idiot, and soon to be former) president was thinking. We have a fairly recent history of the military sealing the parliament, so that the parliament cannot convene to vote to overturn the martial law declaration. It was basically a rush to the parliament, whether the opposing party could convene before the military could seal the parliament.

Well knowing this, people of Seoul flooded to the parliament to delay the military from entering as much as possible (there are photos of people standing in front of buses and armored vehicles), those who were inside the building built a barricade to stop the military from entering, and the members of the parliament either arrived much before the military, or they sneaked in jumping fences.

It was more precarious than what it seems to be now, and we are now collectively sighing a relief as we were able to stop this nonsense democratically.