DUBAI - A policeman was shot dead by masked gunmen in the Qatif district in Saudi Arabia's oil-producing Eastern Province on Wednesday, state news agency SPA said, the latest in a string of attacks there this year. Four assailants opened fire on a police station before dawn, SPA reported. Qatif, which is both a city and the name of a district, is home to many Shi'ite Muslims, who form a minority in the conservative Sunni Muslim kingdom. Qatif was one of three Saudi cities targeted in coordinated bomb attacks on July 4. A suicide bomber struck near a Shi'ite mosque killing himself and two others.