The attacker detonated his explosives in a kitchen outside the prayer hall. Some reports said gunfire continued from other attackers after the blast.
A witness, Hussein Endali, said he heard police shouting before an explosion ripped through the courtyard. “I sat in my car for 30 minutes while gunfire was going on,” Endali said, adding that he saw at least three dead bodies.
Kabul police said four people were dead, including three civilians, and five were wounded. The numbers were expected to rise. Local media said six people had been killed.
Al-Zahra mosque in Dasht-e Barchi is often visited by officials and politicians. It was unclear whether any dignitaries were among the victims.