An undisclosed number of people were killed and wounded today, police said, in the worst episodes of the simmering unrest that has gripped South Africa during the last two months.

The deaths came as police attempted to end fierce rioting in Colored (mixed race) areas of Cape Town. Several of the Colored neighborhoods around the port city appeared to be in a state of siege, as widespread stone throwing, looting and arson broke out, according to the South African Press Association, a news agency. Police sealed off certain areas in an attempt to quell the rioters.

The clashes climax a period of escalating tensions between Coloreds and the authorities that began in April when Colored high school students boycotted classes to protest educational systems segregated by race in this apartheid society.

Although police gave no indication of the number of casualties in the rioting, unconfirmed reports in the South African press said at least 15 people were killed and 50 wounded. The South African Press Association said police closed all channels of information about the death toll to the press.

The deaths indicate that the police have ended their reliance on nonlethal weapons such as tear gas, batons, rubber bullets and birdshot in attempts to halt the disturbances.

The knifing death of a white police officer Sunday in a clash has caused feelings to run high among police in the Cape Town area. The dead officer was the first policeman to die as a direct result of unrest since the 1976 outbreak of widespread violence involving South Africa's Colored and blacks. o

Other Colored and black townships across the country remained tense, but so far only minor incidents had occurred until yesterday when 35 people were wounded in Soweto and Bloemfontein. But the deaths tonight in Cape Town may trigger increased violence across the country.

A blanket police ban to keep all press from entering trouble spots in the country will continue indefinitely, a police spokesman said today.

Meanwhile, Minister for Colored Affairs Marais Steyn tonight announced that due to the unrest he has ordered several teacher-training colleges for Coloreds to close early for vacation. They will not reopen until mid-July.

Police had said earlier today that intermittent disturbances in the Cape Town area had been broken up mainly with tear gas, and calm appeared to have been restored. But as darkness fell, violence erupted. There were reports of cars stoned and shops looted and set afire.Roads were barricaded with burning tires and drums.

The Colored areas hit by the turmoil include Elsies River, Bonteheunel, Ravensmead and Retreat, which are all part of the Cape Flats, a sandy plain at the back of a table mountain that abuts the city of Cape Town. Sections of the Cape Flats were sealed off by police tonight.

One primary school was reported ablaze in the Colored community of Elsies River, where two youths died May 28 in an incident with four policemen.

Chief of police of the western Cape, Brig. J. F. Rossouw said a "criminal element" had taken over and was "looting and setting fire to property belonging to their own people," according to the South African Press Association.

The Cape Times neswpaper reported that two ambulances were seen moving into the area of Retreat about 6:30 tonight.

Cape Town has been the focus of a series of boycott actions by the Colored and black communites during the two-month period of unrest. The school boycott began in mid April and was followed by labor strikes. Consumers have been boycotting meat in sympathy with a strike by meat packers for almost a month.

For the past week, many commuters in the colored and black townships have shunned buses to protest a fare hike.

More workers stayed away from work as a sign of protest in Cape Town yesterday than in any other part of the country, heeding calls by black and Colored organizations to observe the anniversary of the outbreak of bloody riots in Soweto four years ago on June 16.

Absenteeism in Cape Town was as high as 60 to 70 percent in some firms, the South African news agency reported.

Confusion reigned at the city's D. F. Malan airport when the protesters blocked access roads tonight. Air commuters watched vehicles arrive at the airport with shattered windshields and injured passengers.