A Mozambique poll observer was shot dead on Monday in a ruling party stronghold, the latest killing in the run-up to next week's elections, a monitoring group said.Gunmen fired several shots at Anastacio Matavele - head of a local election observation mission - as he was driving away from a workshop in Xai-Xai, the capital of the southeastern Gaza province."He was immediately taken to hospital, where he was confirmed dead," said Sala da Paz, a group that monitors election-related violence.The attackers were involved in a car accident as they fled the scene, said the group. One died in the crash, another taken to hospital and a third was arrested."Local observers have stated that the three assailants are known members of the riot police unit," Sala da Paz added."His death confirms that we are witnessing one of the most violent electoral campaigns."Mozambique is trying to shake off the legacy of decades of unrest after the completion of a historic treaty in August between the government and former rebel group Renamo, now the main opposition party.President Filipe Nyusi is vying for a second term against Renamo's Ossufo Momade and two other candidates in the elections on Tuesday next week.Gaza is a stronghold of Nyusi's Frelimo party.The electoral observation mission claims 38 people have died since the start of the campaign, hordes injured and dozens arrested.While most deaths were caused by traffic accidents, the mission accuses Frelimo supporters of attacking opposition members, blocking campaigns and burning their homes.Junta Militar da Renamo - an armed breakaway faction of Renamo rebel group that opposes the upcoming poll - has also claimed several attacks over the past month.Frelimo has dominated power for more than four decades and Nyusi is widely expected to win.After Mozambique gained independence from Portugal in 1975, Renamo fought a brutal civil war against the Frelimo government that left a million people dead before fighting stopped in 1992.