Police said a dozen people were killed and 15 more were injured in the blast that likely targeted the mosque's imam. At least 12 worshippers were killed in an explosion at a mosque in the Afghan capital during Friday prayers, police said.
People had gathered in the Kabul mosque on the second day of the Mulsim holiday Eid Al-Fitr, also the second day of a planned three-day ceasefire between Taliban insurgents and the Afghan government.
Ferdous Faramarz, a police spokesman, said the mosque's imam was among the dead, adding that 15 other people were injured by the blast.
What we know about the explosion
Investigations were underway, but Faramarz said the imam was likely the target of the attack.
Explosives had been placed inside the mosque before the prayers, he added.
Afghan broadcaster TOLO News tweeted an image showing the damage done to the mosque.
Afghanistan sees spike in violence
A three-day truce with the Islamist Taliban came into effect on Thursday, and was expected to give respite to families celebrating Eid and allow people to visit relatives in Taliban-controlled areas.
It was the fourth ceasefire in the last two decades of conflict.
The Taliban had captured a strategic district close to Kabul shortly before the ceasefire came into effect.
Several attacks in the capital have been claimed the local Islamic State affiliate, but both the Taliban and government continue to blame each other.
The country has been mired in violence in recent weeks after the United States and NATO began withdrawing troops from Afghanistan.
Last week, a car bombing killed more than 90 people, many of them were schoolgirls.