Two policemen were shot dead after unknown gunmen driving a SUV fired at them in the Karama district south of Sinai's Arish on Friday, eyewitnesses reported.
A conscript was killed while standing guard at an army tank at the Arish Hospital, security sources said.
Unknown men yanked the conscript's gun and shot him dead, the sources added.
Two policemen, Ramadan Moawad Mohamed and Tamer Mohamed Abdel Wahab, were killed in the Masa'eed district after gunmen shot them in the head.
Security bodies in Sinai warned policemen against walking along while wearing their uniform to avoid getting shot.