Two mortar shells were behind the powerful explosion which rocked the North Sinai city of Arish earlier on Tuesday, security sources said.
A mortar shell landed near a zoo and the Arish antiquities museum and the other landed on an abandoned house near the zoo, according to the sources.
No casualties occurred due to the curfew.
The blast took place near North Sinai governorate's building.
It was followed by heavy gunfire from security forces.