Gunmen wearing military uniforms shot dead a former Burundian security chief who was a close ally of President Pierre Nkurunziza on Sunday, the presidency and witnesses said, heightening tensions after a disputed presidential poll, according to Reuters. General Adolphe Nshimirimana, who was in charge of the president's personal security at the time of his death, was killed in a car alongside three of his bodyguards in the Kamenge district of the capital Bujumbura, the sources said.