Black gunmen burst into a church Sunday, attacking the mostly white congregation with two hand grenades and automatic gunfire. Ten people were killed and 53 were wounded, police said.
The assault on St. James Church in suburban Cape Town was the deadliest in a series of attacks this year that have targeted white civilians.
"I just saw a door burst open and I heard shooting. I dived for cover and then there were two explosions," the Rev. Brian Cameron Cameron said.
He said there were only adults in the church at the time.
The attack came the night before black and white political parties negotiating an end to apartheid planned to unveil a preliminary draft of a constitution.
There was no immediate claim of responsibility or proof that the attack was linked to the negotiations. Politically motivated attacks against white civilians were extremely rare until late last year. There have been at least half a dozen since last November, leaving more than 20 whites dead.
The attacks against whites have not disrupted the negotiations, but they have heightened racial tensions as the country approaches its first multiracial election in April.
In several cases, the Pan Africanist Congress, a radical black group, has claimed responsibility or been accused of involvement by the police.
Police initially said that whites may have been among the attackers. But a police spokesman said witnesses mistook for an assailant a white member of the congregation who chased after the blacks and fired shots at them.
President Frederik W. de Klerk's office said the "attack on a church introduces a new and horrifying element into the cycle of violence."
Anglican Archbishop Desmond Tutu called the massacre the "most foul, despicable thing imaginable."