A homemade bomb killed two policemen and wounded another two in the capital of Egypt's restive North Sinai province, state media reported late on Thursday.
There was no immediate claim of responsibility for the blast in Al-Arish.
The attack comes days after another homemade bomb exploded near the Supreme Court in downtown Cairo on Tuesday night, injuring 12 people in the second attack in the Egyptian capital in less than a month.
Last month, a bomb blast near the Egyptian foreign ministry killed three policemen in the worst attack in central Cairo for months. Islamist militant group Ajnad Misr claimed that attack.
Security forces are struggling to quell an Islamist insurgency that has killed scores of soldiers and policemen in the peninsula, which borders Israel and the Palestinian Gaza Strip.
The attacks surged after the military overthrew Islamist President Mohamed Mursi last year and the militants extended their reach to the Egyptian mainland with a series of bombings.