The bomb was left directly outside an entrance to the Eidgah Mosque in Kabul. The mosque was holding a memorial service for the mother of Taliban spokesman Zabihullah Mujahid. Today Taliban spokesman Mr Mujahid tweeted: "A bomb blast rocked a gathering of civilians near the entrance of the Eidgah Mosque in Kabul this afternoon. This has left a number of civilians dead."
There has been a rise in extremist groups within the country that are a direct challenge to the Taliban's primacy.
The bomb attack raises the possibility of a wider conflict between extremist groups in Afghanistan.
Factions within Afghanistan have been fighting for control since 2015.
The Taliban and ISIS are enemies and have fought bitterly since 2015 when Isis formed the Islamic State-Khorasan Province (ISKP) in Afghanistan.
The movement of ISIS into Afghanistan came at a time when the group sought to extend its geographical reach beyond Iraq and Syria.
The Taliban launched an offensive to clear ISIS out of the Jowzjan area of Afghanistan.
The Islamic Movement of Uzbekistan has joined with ISIS in opposition to the Taliban.
Emergency NGO, an Italian-funded hospital in Kabul, has now tweeted it had received four people wounded in the blast.
Emergency NGO today tweeted: "Kabul explosion in PD1.
"It happened outside Eid Gah Mosque.
"Four wounded people received at our hospital Afghanistan."
Speaking to AFP a shopkeeper called Ahmadullah, who was near the mosque at the time of the attack, said: “There was the sound of an explosion.
"It happened near the Eid Gah Mosque and was followed by gun firing.
"Just ahead of the blast the Taliban had blocked the road to hold a prayer ceremony for Zabihullah Mujahid's mother in Eid Gah Mosque."
Journalist Habib Khan tweeted: "A number of people were killed and wounded in a blast in Kabul that targeted mourning ceremony for mother of a Taliban spokesman, Zabihullah Mujahid, in front of the famous Eidgah mosque, on Sunday."