UNITED NATIONS, May 9 (Xinhua) -- The United Nations World Food Programme (WFP) has condemned the murder of a member of staff in north-western Kenya, the agency said in a report. Silence Chirara, a 37-year-old father of two, was ambushed and shot dead by unidentified gunmen Wednesday while driving a clearly marked UN vehicle in the town of Lokichoggio. The gunmen escaped. Chirara, a Zimbabwean national who joined the WFP in 1996, started working in Lokichoggio in March 2006 as the coordinator of the WFP's logistics operation for southern Sudan. "In all the places that Silence served, he was an incredible source of comfort and help to his colleagues. He was a valued Logistics Officer known to never step away from a challenge. This is a moment of great sorrow, for Silence's family, especially his wife and two children, friends and those at WFP who worked side-by-side with him over the years," said WFP Executive Director Josette Sheeran. UN Security and the Kenyan police are investigating the crime. It is the second such killing of the agency's staff in Kenya this week. Earlier this week, a WFP truck driver from Somalia was shot dead by militiamen who stopped the agency's food convoy at an illegal checkpoint.