Seoul, South Korea - South Koreans took to the streets Wednesday for a day of rage laser-focused on President Yoon Seok Yeol, whose failed attempt at imposing martial law sparked turmoil.

The streets of Seoul teemed with protesters and police throughout the day as labor unions called a general strike and the opposition demanded Yoon step down and face charges of insurrection.

Outside the National Assembly, where just hours earlier lawmakers voted to block Yoon's martial law declaration, the crowd was united in their wrath against the conservative former prosecutor.

"It was a self-coup, intended to protect himself and his wife," one man shouted – a reference to the myriad scandals that have engulfed the first lady since Yoon's tenure began in 2022.

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With few signs of fatigue from a sleepless night in which they feared Yoon was attempting to reverse decades of democratic progress, the crowd waved multicolored signs and sang South Korea's national anthem.

Opposition politician Cho Kuk accused Yoon of having "attempted a coup through treason, military rebellion, and violations of constitutional and legal provisions."

And former presidential candidate Lee Jae-myung – who livestreamed his late night vault over a fence to get into the parliament – hailed "citizens who risked their lives, ready to face bullets" to defy the martial law declaration.

He said the president had lost all ability to make "normal and reasonable judgment".

Another opposition official described Yoon as "abnormal".

"Abnormal president, with the abnormal presidential wife, tried to protect the abnormal power," said Kim Min-seok, a senior Democratic Party official.

Opposition lawmakers have submitted a motion to impeach Yoon, which requires the support of two-thirds of the parliament and at least six Constitutional Court judges.

The motion could be put to a vote by Friday.

Protests that erupted across Seoul also featured many younger faces who said the experience had awoken them to the fragility of the country's hard-won democracy – reminiscent of the 2016 protests that brought down former President Park Geun-hye.

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"We have to defend it," Shin So-yeon, a woman in her 20s, told AFP. "There is no other option."

Others expressed shock that the country – ruled for decades by a series of authoritarian regimes, backed to varying degrees by the US – had come so close to turning back the clock on almost 40 years of democracy.

"It was like something out of a history textbook," Park Su-hyung (39) said.

"Our democracy will be trampled if we keep Yoon in office a moment longer."

At a gathering in Seoul's central square later Wednesday, protesters handed out hot drinks and candles as they readied for another long night.

Demonstrators later marched on the National Assembly, determined to keep up the pressure until Yoon steps down.

Thousands of people gathered at either end of the protest march, chanting and calling for Yoon to resign.

Insisting she "had to be here tonight," Choi Moon-jung (55) told AFP: "The president is crazy."