Egypt’s security forces have since 2014 been battling a Daesh affiliate in northern Sinai, where militants have mostly hit police and soldiers but also occasionally targeted infrastructure and businesses.
Two security sources in Al-Arish, the area capital, said armed men attacked the convoy, which was carrying coal to a cement factory.
The bodies of the truck drivers, all shot to death, were taken to the morgue of Suez public hospital, four medical sources said.
A military spokesman said there was no official statement. An interior ministry official did not respond to a request for information.
No group immediately claimed responsibility for the attack.
“They have threatened us repeatedly, asking that we don’t work for the army’s companies. We informed the factory management of the threats and asked them for more protection,” one local truck driver, Ismail Abdel-Raouf, told Reuters.
Hundreds of police and soldiers have been killed since the insurgency quickened pace in northern Sinai after the 2013 ouster by the military of then-president Mohamed Mursi of the Muslim Brotherhood during massive protests against his rule.
A home-grown jihadist group, Ansar Bayt Al-Maqdis, declared allegiance to Daesh in 2014 and has since tried to spread outside the peninsula by targeting Christians with attacks on churches on the mainland.
President Abdel-Fatah El-Sisi, who presents himself as a bulwark against militants in the Middle East, has said Daesh fighters might try to enter Libya and Egypt after their defeats in Iraq and Syria.
Security forces have also faced attacks in the western desert region bordering Libya, where security sources say a former Egyptian special forces officer turned jihadist allied to Al-Qaeda was responsible for an ambush on a police operation last month.