At least five blacks were killed and dozens more wounded today as police put on a massive show of physical force in crushing a planned protest march. More than 40 of the march's organizers and participants were arrested.

The worst violence occurred in this sprawling black township, where police in riot gear used shotguns, tear gas and rubber bullets to break up a crowd of several thousand marchers. Some of the protestors then went on a rampage, burning a beer hall and at least five cars. Five men were reported killed and 65 people wounded by police shotgun fire.

In nearby Athlone, a township of Colored, or mixed race, residents, police ignored pleas from clerics leading another group of marchers and charged demonstrators who had gathered peacefully. Hundreds of people, heads bleeding from plastic whip cuts and eyes and throats burning from tear gas, scattered blindly through the narrow streets.

Police later laid siege to a nearby teachers' college, where many protestors had taken refuge, peppering the campus with tear gas and rubber bullets while demonstrators pelted police vehicles with rocks. After allowing some students to leave quietly, police charged the campus and later arrested nine journalists observing the action.

There were scattered incidents on two other campuses and elsewhere outside Cape Town, until now relatively quiet throughout a year of intensifying political unrest that has claimed nearly 650 lives. Opponents warned that the government's refusal to allow peaceful protest today would exacerbate tensions and had triggered the new eruption of violence in this area, which is not among the 36 cities and towns designated under last month's emergency decree.

In yet another display of state power today, South Africa's white-minority government outlawed the country's largest black student activist organization, the Congress of South African Students. It was the first time in several years that the government has banned a political movement.

Today's march had been called by the Rev. Allan Boesak to demand the release of jailed black nationalist leader Nelson Mandela, who is serving a life sentence at Pollsmoor Prison about 20 miles outside Cape Town. Although organizers had promised the march would be nonviolent, officials saw it as a direct challenge to state authority and warned it would be treated as an illegal gathering.

Boesak, a founder of the opposition United Democratic Front and president of the World Alliance of Reformed Churches, was arrested yesterday but other march organizers decided to go ahead.

The government responded early this morning when hundreds of police and soldiers in armored vehicles sealed off the Athlone sports stadium, which had been designated as the starting point for the march.

By 10 a.m., several hundred would-be marchers had gathered instead across the main highway from the stadium. A police lieutenant on the scene spurned requests from clerics for time to move the demonstrators away from the area and, after broadcasting a final warning on a loudspeaker, shouted to his men in Afrikaans, "Clean up!"

They swept into the crowd, slashing with their whips and driving the protestors down several side streets. Many who were knocked down by the first blow were then struck repeatedly before being allowed to get up and flee. The police, half of whom were white and half of mixed race, made three more charges into smaller, scattered groups, while others bundled a group of a dozen protesting clerics and academics into a nearby police van. Among those arrested were the Rev. Abel Hendricks, former head of South Africa's Methodist Church.

At around the same time several thousand protestors here in Guguletu were cut off by police vehicles at the township's entrance and dispersed, according to witnesses. They responded with a barrage of rocks, stoned or burned several vehicles and constructed barricades of burning tires throughout the town.

Police reported four dead at the scene and a fifth man died at a nearby clinic. Clinic officials also reported treating 65 persons for shotgun pellet wounds. Six policemen were reported injured from bottles and stones thrown by the crowd.

Police also sealed off the University of the Western Cape, where Boesak is a Dutch Reformed chaplain. Witnesses said police and students traded barrages of tear gas and rocks throughout the day there.

By noon another crowd had formed outside the Hewat Training College in Athlone and set out for the prison. They got less than a mile before they too were cut off by police vehicles. Holding posters of Mandela and singing the Lord's Prayer, the demonstrators sat down in the road while their leaders pleaded in vain with the police for permission to continue.

After a brief warning, the police again charged with whips and fired tear gas and rubber bullets. More than 20 protest leaders who linked arms at the front of the crowd were arrested.

Hundreds retreated back to the campus, where they dodged tear gas cannisters and set up a makeshift first-aid station in a gymnasium. The school's vice principal, Abu Desai, negotiated a 40-minute reprieve and shepherded hundreds of students from the campus through a hole in a chain link fence while police stood by silently. Some who had been overcome by tear gas had to be carried. Others were crying.

"People, I've only got 40 minutes," Desai pleaded with the students. "Please move, please move quickly."

Then police sealed off the campus and ordered journalists to leave. They fired tear gas rounds at me and two other foreign journalists observing the scene from off-campus, then entered the schoolgrounds and chased off the remaining protestors.

Nine other journalists, eight of them working for foreign news media, were later arrested outside the campus and charged with obstructing police by failing to comply with an order to leave the area. The nine -- who included a three-member CBS camera crew, a reporter and photographer for the Dallas Morning News and photographers for Time, U.S. News and Agence France Presse -- were released without bail but ordered to appear in magistrate's court Thursday .

Later in the day, six students were arrested following a protest outside the campus of the University of Cape Town that turned into another confrontation with police. Seven other persons were arrested outside the prison at Pollsmoor where they attempted to deliver a message to Mandela, a leader of the outlawed African National Congress resistance movement who is serving a life sentence for treason.

Protest organizers said most of those arrested today were charged under South Africa's sweeping internal security act with participating in an illegal gathering and would be held overnight before facing a hearing Thursday.

Vice Principal Desai was among many today who contended the police action had been needlessly harsh and provocative. "The police have overreacted," he said. "They are panic-stricken. I'm sure in my own mind this could have been handled peacefully."

Appearing at a press conference in Cape Town late this afternoon, the Rev. C.F. Beyers Naude, general secretary of the South African Council of Churches, said today's crackdown was "a clear indication about the government's hysteria in the face of peaceful protest. My deep concern is that if not even peaceful protest of this kind is permissible, what then remains?"

Boesak's wife Dorothy also appeared at the press conference. She said a security police colonel had visited her house today to inform her that her husband had been transferred to a prison in Pretoria, the South African capital, and to assure her he was being well cared for.

Nonetheless, she said, she was "very very worried." She said when she had asked how long her husband -- who is being held under a provision of the security law that allows for indefinite detention without access to lawyers or family -- would be jailed, the police officer replied, "It might be a few days or it might take some time."

In banning the Congress of South African Students, or COSAS, the government is outlawing one of the main affiliates of the opposition United Democratic Front and an organization that has branches in dozens of black townships. Hundreds of its members have been detained since the emergency decree five weeks ago and many others have gone underground.

It is the first time the government has banned a student group since nearly 30 were outlawed in 1977 following a year of unrest that began in the black urban center of Soweto.

Minister of Law and Order Louis le Grange gave no explanation in announcing the ban but police officials have long insisted COSAS activists are some of the main "instigators" of the political violence that has wracked South Africa since last September.