An improvised explosive device detonated early on Monday morning at the courthouse of Samannoud, a city in Egypt's northern Al-Gharbiya Governorate, reported Reuters' Aswat Masriya.
No injuries or fatalities were reported.
Explosives experts defused another IED uncovered in the same location, the same source added.
According to a Ministry of Interior report released earlier this month, explosives experts have defused more than 150 devices in various governorates over the past three months.
After the deposal of Islamist president Mohamed Morsi on 3 July last year, attacks against security forces – including explosions – escalated rapidly. Around 500 police and military personnel have been killed since then.
The government has accused Morsi's supporters – particularly the Muslim Brotherhood group from which he hails – of orchestrating the attacks. The Brotherhood, now designated by an Egyptian court as a terrorist organisation, has systematically denied any link to violence against the authorities.