Sinhalese extremists seeking to disrupt Thursday's regional elections detonated a bomb in a crowded market, killing four people, a Sri Lankan military official said. The official said Sinhalese radicals on Wednesday also fatally shot a candidate for the southern District Council. Authorities blamed the pre-election violence on the People's Liberation Front, an ultra-nationalist group from Sri Lanka's ethnic Sinhalese majority. District Council elections were called under terms of an Indian-brokered peace accord signed on July 29, 1987, and intended to end a separatist war by the Tamil minority. The war has cost more then 8,000 lives since 1983. Sinhalese radicals claim the pact makes too many concessions to Tamils and have vowed to kill anyone who supports it. A total of 166 candidates are competing for 53 seats on the newly created southern District Council, the seventh to be elected since April 28. Attacks by the Sinhalese radical group since India and Sri Lanka signed the peace agreement have taken the lives of 24 council candidates and more than 300 other people, including civilians and party workers. The bomb Wednesday exploded in the market at Weligama town, 75 miles south of Colombo. The military official, who spoke on condition of anonymity, said the four people killed were Sinhalese civilians. He said the candidate, 52-year-old A.S. Dayawansa, was shot to death while campaigning on Wednesday in the southern district. He was a member of the opposition United Socialist Alliance. Five deaths were reported Tuesday, including one candidate, a policeman and a civilian. Other violence in the past two days included the burning of government buses and several courthouses. Storekeepers said Sinhalese extremists told them to close Wednesday, and police said the group ordered a ``curfew'' on Thursday to keep people from leaving their homes to vote. Sinhalese, most of whom are Buddhists, are more than 75 percent of Sri Lanka's 16 million people and Tamils, predominantly Hindu, make up 18 percent. Tamils claim discrimination by the Sinhalese, who control the government and army, and rebels seek a separate homeland in the Tamil-dominated north and east to be called Eelam. The peace agreement called for Tamil rebels to lay down their arms in exchange for more autonomy in northern and eastern Sri Lanka, but the largest insurgent group continues to fight. India has more than 50,000 troops on the island trying to end the rebellion. It became involved because it is the region's dominant power and has 60 million Tamils in southern Tamil Nadu state. District Council elections in the Tamil-dominated areas have been delayed by the fighting, but officials hope to hold them next month.