Peshawar, Rabi'II 16, 1434, Feb 26, 2013, SPA - Police say gunmen have shot dead a police officer protecting a team of polio workers during a U.N.-backed vaccination campaign in northwestern Pakistan. Police officer Fazal Wahid says no polio workers were wounded in Tuesday's attack in the districts of Mardan in Khyber Pakhtunkhwa province. No one immediately claimed responsibility for the attack, according to a report of the Associated Press. --SPA 13:55 LOCAL TIME 10:55 GMT www.spa.gov.sa/1082161