SEOUL, South Korea - President Roh Moo-hyun was stripped of his constitutional powers today in an unprecedented impeachment vote that rattled a government already struggling with the North Korean nuclear crisis and a sluggish economic recovery.

Thousands of the president's supporters rallied in front of the National Assembly building in a candlelight vigil.

"We oppose impeachment! This is a mutiny!" read banners held by the chanting protesters.

The parliament voted to impeach Roh after hours of scuffles and protests that included one Roh supporter setting himself on fire and another man trying to drive his car up the parliament steps and into the building.

Prime Minister Goh Kun was to assume Roh's duties, while the Constitutional Court decides whether to unseat the president. The powers include his role as commander in chief of South Korea's 650,000-member military, which faces off against communist North Korea's 1.1 million armed forces across the world's most heavily armed border.

Goh instructed the Defense Ministry to heighten military vigilance along the border, although the ministry said it has detected no unusual military movement.

The vote marked a spectacular setback for Roh, a 57-year-old, self-made human rights lawyer who came to office 13 months ago on a populist ticket that promised better relations with communist North Korea and a more equal footing with the country's biggest ally, the United States.

His tenure was marked by corruption scandals. But today's vote - the first time South Korea's parliament has impeached a president - was a crowning embarrassment for the feisty, independent leader.

The matter now goes to the Constitutional Court, which has 180 days to approve or reject Roh's ouster. If it approves the ouster, a special election will choose a new president.

Dozens of police buses with bars on the windows blocked about 3,000 Roh supporters from marching on the sprawling National Assembly complex. No major clashes were reported.

Earlier today, dozens of Roh critics also rallied in the area, dancing on the sidewalks and chanting: "Today is a national holiday!" They soon dispersed.

The pro-Roh Uri Party, which had tried to physically block the vote by commandeering the National Assembly podium from which votes are called, also announced its 47 lawmakers would resign en masse to protest.