A train driver was killed and at least 90 other people injured Tuesday when two crowded commuter trains collided in Johannesburg, South African officials said, adding that emergency teams had cut one woman free from the wreckage.

"Paramedics, along with various services, arrived on the scene and found the wrecked trains blocking the tracks completely," Russel Meiring, spokesman for the ER24 paramedic group, said.

Thousands of demonstrators readied to march through central Johannesburg on Thursday to protest against a spate of attacks on immigrants, after further raids by the authorities on suspected gang hideouts.

Two people were arrested late Wednesday when police, backed by soldiers, stormed a workers' hostel in the city's crowded Alexandra township.

South African President Jacob Zuma on Thursday appealed for calm as a wave of anti-immigrant violence spread to Johannesburg, raising fears the country's dire economic woes could spark widespread unrest.

At least six people have been killed in the last two weeks in attacks in the Indian Ocean city of Durban that targeted shops and homes owned by Somalis, Ethiopians, Malawians and other immigrants.

South African police said Sunday they have discovered the frozen corpses of four newborn babies in freezers at a house in the southern city of Mthatha.

Acting on a tip-off, police raided a house on Saturday and made the grim discovery of the infants estimated to be aged between just one and two months.

Two more people have died as the week-long looting of foreign-owned shops continued in townships around South Africa's economic capital Johannesburg, police said Monday.

The men were killed Sunday night during a raid on a shop owned by a Somali immigrant in central Johannesburg.

South African police said Friday they had arrested 121 people after mobs went on a looting spree of grocery stores owned by foreign nationals in Johannesburg's Soweto township.

Dozens now face charges of public violence -- including a police officer caught on film participating in the looting, Lieutenant-General Lesetja Mothiba, police commissioner of South Africa's economic hub Gauteng, said at a press conference Friday.

Eight South African workers died Monday when a building under construction collapsed, and more people were feared trapped under the rubble, emergency workers said.

The laborers were working on a double-storey residential building on a private estate in Meyersdal south of Johannesburg when it collapsed.

A 5.3 magnitude earthquake struck South Africa on Tuesday, shaking buildings in the commercial capital Johannesburg and killing one man in a gold mining town.

The quake, centered south of Johannesburg, was reportedly felt as far afield as neighboring Botswana and Mozambique.

Vote counting in South Africa's election that returned Nelson Mandela's ANC to power wrapped up on Saturday, while the army was deployed overnight to quell violence in a Johannesburg township over alleged voter fraud.

Completed results showed the African National Congress won 62.15 percent of the ballots, while the main opposition Democratic Alliance came in second with 22.23 percent.

Eight of the nine gold mineworkers trapped underground in a shaft west of Johannesburg have been found dead, the National Union of Mineworkers said Thursday.

"Eight of the nine mineworkers who were missing at Doornkop Mine are found dead," the union said in a statement. A search was ongoing for the ninth man still missing.