The Afghan Interior Ministry said that the bomb exploded during Friday prayers at the Sher Shah Suri Mosque, which is located in the western part of Kabul.
“Based on our initial information, at around noon, explosives placed inside the mosque detonated during Friday prayers,” a ministry spokesman, Tariq Arian, said.
Prayer leader Mofleh Frotan was among those killed in the attack.
No group immediately claimed responsibility for the blast.
An attack on a mosque compound near a fortified diplomatic district in Kabul earlier this month was claimed by the Takfiri Daesh terrorist group.
The United Nations (UN) has recently warned of an alarming uptick in violence against civilians and a “striking deterioration” in upholding international humanitarian law in Afghanistan.
Violence has surged despite a deal between the Taliban and the United States. Official data shows that Taliban bombings and other assaults have increased 70 percent since the militant group signed the deal with the United States in February.
Under the agreement, the US will withdraw its forces from Afghanistan, and the Taliban will refrain from attacking international occupying forces. The militants made no pledge to avoid attacking Afghan forces and civilians.
The United States and its allies invaded Afghanistan in October 2001. While the invasion ended the Taliban’s rule in the country, it failed to eliminate the group.