SEOUL, South Korea (AP) _ The usual frenetic activity of the South Korean capital swirled today around a U.S. government building in the heart of the city that was occupied for the third day by about 70 student protesters.

The students occupied the second floor library of the four-story U.S. Information Service building on Thursday, demanding that President Chun Doo- hwan's government accept responsibility for crushing a rebellion five years ago in the southern city of Kwangju. At least 191 people died in the incident.

They also want an apology from the United States for what they say was its part in the incident. The United States denies any involvement.

Except for reports of two policemen injured when students charged into the building, there has been no violence.

Units of plainclothes police have maintained positions along the sidewalk in front of the building, but larger contingents of uniformed police have been kept a distance away and largely out of sight.

Traffic has been allowed to continue on the busy thoroughfare in front of the U.S. building, resulting in congestion typical of downtown Seoul.

Pedestrians have been restricted from getting too close to the U.S. government center, but clusters of reporters and photographers have been allowed to maintain their vigils on the sidewalk.

Reporters have been able to communicate with the students, who from the start have put signs in windows stating their demands. Journalists have made their own signs, posing questions for those inside.

Crowds of curious have gathered in front of the Lotte Hotel, Seoul's largest, directly across the street. On Friday, there also were family members of the student protesters, some mothers waving handkerchiefs toward the windows and weeping.

While part of the U.S. mission in Seoul, the information center is not in a compound and is about four blocks from the embassy itself. The street it faces leads to city hall plaza about a block away, and is one of the city's main traffic hubs.

Next door is a high-rise office building with an Italian restaurant that claims to be the oldest such facility in Seoul.

The students barricaded themselves into the library with desks, chairs and bookshelves. However, they have kept up intermittent talks with embassy officers, at times lowering the barricades and even setting up a table where talks could be held.

The students could be seen through the windows moving about the library, at times chanting slogans or singing protest songs. One account said some of them stood at attention at 5 p.m., the normal practice here when the South Korean national anthem is played over loudspeakers.

While standing firm on their demands, the students said from the start they wanted to avoid violence. U.S. officials have been able to move in and out of the building without hindrance. They have rotated shifts in order to have officers on duty at any time of the day or night that the students want to talk.