Gunmen killed six Egyptian soldiers in an attack on a military checkpoint north of the Suez Canal city of Ismailiya on Monday.
In a separate incident, a massive explosion, possibly from a car bomb, damaged the four-story security headquarters in a southern Sinai town, killing two people and wounding 48.
The security officials said the toll from the attack in the town of al-Tour was likely to rise as rescue workers and residents search for victims under the rubble.
In yet another security incident, an Amaadi Satellite Earth station in Cairo was hit by an RPG attack.
