Radicals firebombed a U.S. Army facility and a ruling party office and seized a government building Friday, demanding the arrest of a former president and withdrawal of American troops.

The incidents came a day after thousands of students took part in nationwide rallies against former President Chun Doo-hwan in one of the worst street protests in South Korea in recent months.Chun has been under public fire for alleged misuse of power, corruption and violation of human rights during his seven-year tenure that ended in February. Chun, a former general, seized power with military backing in 1980.

U.S. authorities said a dozen youths Friday threw six firebombs into the compound of a U.S. Army engineering installation and fled, shattering windows but causing no injuries.

Radicals have demanded the withdrawal of 42,000 U.S. troops in South Korea as part of their anti-U.S. campaign.

About 20 students hurled firebombs at an office of the governing Democratic Justice Party in the western port of Inchon, shattering windows, police said. No injuries or arrests were reported.

In another attack, on the Office of National Tax Administration in downtown Seoul, five students demanding Chun's arrest seized a third-floor office for a half-hour before being overpowered by police.

Two of the students jumped onto mattresses placed by police on the ground outside the building. Police said the two were slightly injured.

Up to 380 people, mostly police, were injured and about 100 protesters are under questioning after more than 29,000 people took part in anti-Chun rallies across the country Thursday, newspapers reported Friday.

About 9,200 rounds of tear gas were used against 18,700 firebombs hurled by students, police said, adding that students attacked six government party offices, eight police substations and two government buildings.

Student leaders said Friday they would continue an anti-government campaign to press for Chun's arrest and punishment for alleged corruption and human rights abuses.

Students also vowed to join another march Saturday to Chun's house, called by dissident groups.

Chun has been under parliamentary investigation on various charges, including his alleged role in putting down a 1980 civil uprising in the southern city of Kwangu. About 200 people died in the military suppression of the uprising.