THE peace accord signed last month by all the major parties in South Africa brought a burst of hope. That hope is imperiled by the country's continuing violence. Battle lines are being redrawn between the government and the African National Congress, between the ANC and the Inkatha Zulu movement, between township residents who regularly see neighbors killed or wounded and police forces accused of collaborating with the killers.The fundamental line, however, is between those committed to a peaceful transition to nonracial government and those using violence to thwart that transition. Recent outbreaks of killing suggest that gangs of professional assassins are at work. This has been planned killing, not just spontaneous street violence between rival black groups. Sam Ntuli, the murdered community leader from the Tokoza township outside of Johannesburg, was known as a peacemaker who was committed to making the September accord work. Those who planned his murder were aiming at the peace accord, too. Mr. Ntuli's funeral became the scene of more violence, as gunmen mowed down 18 people. The police were out in force, which raised the question of how the murderers were allowed into the area. The administration of President Frederik de Klerk hasn't yet dealt with such questions as vigorously as it needs to. Mr. De Klerk has consistently condemned the violence, but he has shied away from calls for thorough, independent investigations of charges of police complicity. The peace accord sets up procedures for such probes. The government's adherence to the accord is being put to the test by the current violence. Can it prove to black South Africans that their security is a top concern? ANC leader Nelson Mandela has blamed De Klerk for the killing, saying the government could stop it if it really wanted to. The president hotly rejects those charges and in turn criticizes the ANC for its refusal to categorically reject violence. For all the hard-edged words of the moment, De Klerk and Mandela have shown they can sit down, together with other South African leaders, and come up with a plan for peace. September's accord remains a map toward peaceful political behavior and the all-parties conference that will be a crucial step toward a new, more just political order. People of good will in South Africa have to persist in implementing the accord even as the bullets fly. Those whose tool is violence can't be given the victory.