A suicide bomber has targeted a mosque in the northern Afghan city of Kunduz during Friday prayers, killing at least 50 people, BBC reports citing officials.
Images posted on social media said to be of the aftermath of the blast show extensive damage in the mosque, used by the minority Shia Muslim community.
No group has yet claimed responsibility for the attack.
Sunni Muslim extremists, including the local Islamic State (IS) group, have targeted the Shia community because they consider them to be heretics.
IS-K, the Afghan regional affiliate of IS that is violently opposed to the Taliban, has carried out several bombings recently, largely in the east of the country.
Zalmai Alokzai, a local businessman who rushed to a hospital to check whether doctors needed blood donations, described seeing chaotic scenes. "Ambulances were going back to the incident scene to carry the dead," he told AFP news agency.
The continuation of violence in the country, even after the Taliban takeover in August, has been met with dismay by ordinary Afghans.
The Taliban took control of Afghanistan after foreign forces withdrew from the country following a deal between the US and the Taliban, two decades after US forces removed the militants from power in 2001.