Suicide bombers attacked a Shiite mosque in the southern Afghan city of Kandahar during Friday prayers, witnesses said, killing at least 41 people and injuring scores more.
The assault came just a week after a suicide attack on Shiite worshippers at a mosque in the northern city of Kunduz, which was claimed by the Islamic State group
There has not yet been any claim of responsibility for the attack in Kandahar, the spiritual heartland of the Taliban.
"Our initial information shows it was a suicide bomber who blew himself up inside the mosque. We have launched an investigation to find out more," a local Taliban official told AFP.
Hafiz Abdulhai Abbas, director of health for Kandahar, told AFP: "Information from the hospitals shows 41 killed about 70 wounded in today's mosque attack."
At least 15 ambulances were seen rushing to and from the scene, as Taliban security threw a cordon around the area.
"We are overwhelmed," a doctor at the city's central Mirwais hospital told AFP.
"There are too many dead bodies and wounded people brought to our hospital. We are expecting more to come. We are in urgent need of blood. We have asked all the local media in Kandahar to ask people to come and donate blood."
Eyewitnesses spoke of gunfire alongside the explosions, and a security guard assigned to protect the mosque said three of his comrades had been shot as the bombers fought their way in.
Sayed Rohullah told AFP: "It was the Friday prayer time, and when we were preparing I heard shots. Two people had entered the mosque.
"They had opened fire on the guards and in response the guards had also opened fire on them. One of them committed a suicide blast inside the mosque."
Two more attackers detonated their bombs in crowded areas outside the main building, he and other witnesses said.
"We are saddened to learn that an explosion took place in a mosque of the Shiite brotherhood in the first district of Kandahar city in which a number of our compatriots were martyred and wounded," tweeted Taliban interior ministry spokesman Qari Sayed Khosti.
Inside the mosque, after the blast, the walls were pockmarked with shrapnel and volunteers swept up debris in the ornately painted prayer hall. Rubble lay in an entrance corridor.
Last Friday, an Islamic State-Khorasan (IS-K) suicide bomber targeted a Shiite mosque in Kunduz, killing scores of people.
The group, a bitter rival of fellow Sunni Islamist movement the Taliban, claimed responsibility for the attacks against Shiite worshippers, whom it regards as heretics.
UK-based conflict analysis firm ExTrac said that if claimed by IS-K, Friday's assault would be the first by the group in Kandahar, and the fourth mass casualty massacre since the Taliban took Kabul.
ExTrac researcher Abdul Sayed told AFP the attack was "challenging the Taliban claims of holding control on the country. If the Taliban can't protect Kandahar from an IS-K attack, how could it protect the rest of the country?"
The UN mission in Afghanistan tweeted: "The UN condemns latest atrocity targeting a religious institution and worshippers. Those responsible need to be held to account."
The Taliban, which seized control of Afghanistan in mid-August after overthrowing the US-backed government, has its own history of persecuting Shiites.
But the new Taliban-led administration has vowed to stabilise the country, and in the wake of the Kunduz attack promised to protect the Shiite minority now living under its rule.
Shiites are estimated to make up roughly 10 percent of the Afghan population. Many of them are Hazara, an ethnic group that has been persecuted in Afghanistan for decades.
In October 2017, an IS suicide attacker struck a Shiite mosque in the west of Kabul, killing 56 people and wounding 55.