The attack, which hit a military base in the coastal city of al-Arish in northern Sinai, also wounded six other soldiers.
The injured have been evacuated to a military hospital nearby.
The attack took place 25 miles away from the town of Bir al-Abd, making it the first major attack in the central Sinai area.
Central Sinai had so far escaped a campaign of Islamist attacks.
It was carried out using assault rifles and some heavier weapons, the sources said.
dailystar.co.uk
