Three Egyptian riot policemen were killed on Tuesday in a rocket attack on their convoy in the Sinai Peninsula, where authorities are fighting a militant group, the interior ministry said.
No group has yet claimed responsibility for the incident.
A ministry statement stated that "unknown" assailants fired a rocket-propelled grenade at the police patrol on the road to the town of Sheikh Zuweid.
One vehicle was struck and three riot policemen killed, while eight others were wounded, the statement added.
Since Egypt's military overthrew first democratically elected president Mohamed Morsi in 2013, some armed groups have stepped up attacks on the army and police with near daily attacks carried out in North Sinai.
Most of the Sinai attacks are claimed by "Sinai Province", the Egyptian branch of DAESH terrorist organisation.