IS is suspected of carrying out the attack on the Fatimiya mosque in southern Afghanistan, which comes a week after another deadly attack in the north.
More than 35 people have been killed after a Shi'ite mosque was hit by explosions during Friday prayers at Kandahar in southern Afghanistan. Around 70 people were wounded.
It's a week since a suicide bomb attack targeted Shi'ite worshipers in Kunduz in the north of the country, killing 46 people, for which the Islamic State group claimed responsibility.
Taliban spokesman Bilal Karimi said an investigation had begun into the latest attack.
A witness said he heard three explosions which rocked the full mosque in the centre of the town. The weekly Friday prayer service is typically attended by large crowds of worshippers.
Another witness, named Murtaza, was in charge of security at the mosque and said he saw two bombers. He said one detonated explosives outside the gate, and the other was already among the worshippers inside the mosque.
He said the mosque's security personnel shot another suspected attacker outside.
Kandahar is the second largest city in Afghanistan and the Taliban's birthplace.
No one has yet claimed responsibility but Daesh, IS-K militants, are an enemy of the Taliban, making this hit significant.
If the attack was carried out by IS, it would be the first major assault by the extremist group in southern Afghanistan since the US departure enabled the Taliban to consolidate control of the country.
Recent attacks in the north, the east and the Afghan capital have cast doubt on the Taliban’s ability to counter the threat posed by IS.