Violence Erupts in Second S. African Black Homeland : Bophuthatswana: Police fire on protesters calling for the leader’s ouster. The eruption follows a coup in Ciskei.

In the week’s second major outbreak of violence in South Africa’s black-ruled territories, Bophuthatswana police Wednesday fired on thousands of protesters demanding the resignation of homeland leader Lucas Lawrence Mangope. At least seven people died, and more than 450 were injured.

The unrest in Bophuthatswana--and rioting that followed a coup d’etat in the Ciskei homeland earlier in the week--was touched off by growing unhappiness with the homeland system, which has stripped millions of blacks of their South African citizenship and placed them under the control of often autocratic black leaders supported by Pretoria.

Many poverty-stricken homeland residents, angered by high taxes and government corruption, want to relinquish their independence and return their land to South Africa. But Mangope, like Ciskei President Lennox Sebe, who was deposed Sunday, has refused to consider such a move.

The growing trouble now threatens to derail President Frederik W. de Klerk’s attempts to open black-white negotiations on a new constitution, which will give South Africa’s black majority its first vote in national affairs.

De Klerk said Wednesday that the government is concerned about the unrest, and he vowed to prevent the situation from “slipping into anarchy.” He added that South Africa’s 45-month-old state of emergency, which gives police sweeping powers, would remain in place as long as unrest prevailed in the country. The main anti-apartheid organization, the African National Congress, refuses to come to the negotiating table until the emergency is lifted.

Bophuthatswana President Mangope declared a state of emergency in parts of his homeland Wednesday and asked South Africa for military assistance to quell the violence. South African security forces, which restored Mangope to power after a 1988 attempted coup, agreed to assist him, Foreign Minister Roelof (Pik) Botha said late Wednesday.

The trouble in Bophuthatswana began when more than 20,000 people marched on a magistrate’s court in Ga-Rankuwa, about 15 miles northwest of Pretoria. Bophuthatswana, home of the Sun City casino resort, is divided into seven separate parts, each surrounded by South African soil, and has about 2 million residents in all.

The protesters Wednesday carried a petition demanding Mangope’s resignation and reincorporation of the nominally independent homeland into South Africa. The petition also complained about escalating rents and taxes and high electricity and water bills.

Calls for reincorporation into South Africa have increased in South Africa’s 10 homelands, four of which Pretoria considers independent, since De Klerk lifted bans on black anti-apartheid groups and freed black nationalist leader Nelson R. Mandela last month.

Most homeland officials and entrepreneurs with a stake in the system have opposed reincorporation, and political analysts predict even more violence in the coming months.

Some protesters in Bophuthatswana carried banners reading: “Away with Mangope’s dompas and his independence.” Dompas are identification passes required of residents by the homeland authorities.

Witnesses said that demonstrators set fire to government offices and buildings in Ga-Rankuwa and later erected barricades of burning tires to prevent troops in armored personnel carriers from entering. Mobs later threw stones at soldiers and police officers, who responded with shotgun fire.

Bophuthatswana authorities cut telephone lines to the homeland late Wednesday, the South African Press Assn., a domestic news agency, reported.

Bophuthatswana, which gained its independence in 1977, was rocked by violence last year when the white minority-led government in Pretoria decreed that two villages in western South Africa would become part of the homeland against their wishes. Mangope had sought control over the two towns, Leeuwfontein and Braklaagte, where much of his political opposition is based.

A bitter dispute over that incorporation led to a weekend of rioting in July, and nine black police officers and two civilians were killed.

South Africa instituted the homelands policy in the mid-1970s to force 11 million of the country’s 27 million blacks into ethnic homelands. None of the homelands are recognized by foreign governments, and all are heavily subsidized by Pretoria, which spends $1 billion annually on the homelands system.

Sebe’s Ciskei government was toppled Sunday by military officers. Sebe, whose tough-fisted rule had lasted 18 years, was out of the country on a trade mission to the Far East at the time and crowds turned out on the streets to celebrate his overthrow.

But the celebrants, many of whom had been drinking heavily, went on a rampage in the homeland of 800,000 on the Indian Ocean coast. Government buildings, factories and other businesses seen as beneficiaries of Sebe’s policies were burned to the ground, and as many as 20 people were reported killed before South African troops stepped in Tuesday to halt the violence.

The situation in Ciskei was calm Wednesday, but businessmen estimated that at least 10,000 people had been left jobless by destroyed factories and they figured the final damage toll would run into millions of dollars.

Nevertheless, the Ciskei Chamber of Industries president, Ray Brentnall, said industrialists met Wednesday and decided to rebuild.