Two Iraqi nationals were killed and two others injured Sunday when unknown gunmen opened fire at a civilian crowd in the northern province of Kirkuk, an interior ministry source said. The gunmen managed to escape, added the source.Meanwhile, Iraqi police arrested four insurgents and seized a quantity of weapons in Al-Askari area of Kirkuk. In another development, the Multi-National Forces announced in a statement that they killed a number of gunmen who attacked their patrol South of al Huwaija in western Kirkuk.