KABUL, Afghanistan (AP) — A bombing inside a mosque in a northern Kabul neighborhood killed four worshippers and wounded over 20 others on Friday, Afghan police said.

Kabul police spokesman Ferdaws Faramarz said explosives had been placed inside the mosque beforehand.

No one immediately claimed responsibility for the explosion. Kabul police say an investigation is underway.

The explosion comes on the second day of a three-day ceasefire announced by the warring Taliban and Afghan government. The pause was for the Islamic festival Eid-al-Fitr, which follows the fasting month of Ramadan.

Until now many of the attacks in the capital have been claimed by the local Islamic State affiliate, but both the Taliban and government blame each other.

The most recent attack last week killed over 90 people, many of them pupils leaving a girls’ school when a powerful car bomb exploded. The Taliban denied involvement and condemned the attack.