Reportedly nearly 100 people were killed and dozens of others were wounded when a blast ripped through a Shia mosque in Afghanistan's northeastern Kunduz province.
According to reports, a suicide bomber was responsible for the blast.
The attack occurred in Kunduz, north of Kabul. No group has claimed responsibility so far.
“This afternoon, an explosion took place in a mosque of our Shiite compatriots … as a result of which a number of our compatriots were martyred and wounded,” Taliban spokesman Zabihullah Mujahid said on Twitter.
Local businessman Zalmai Alokzai told AFP that the scene was chaos. He was in the process of quickly making his way to the hospital to see if blood donations were needed.
"Ambulances were going back to the incident scene to carry the dead," he said.
The United Nations Assistance Mission in Afghanistan called the attack “part of a disturbing pattern of violence” against religious institutions.
"The UN family in Afghanistan is deeply concerned by reports of very high casualties in an attack today in Sayyidabad Shia Mosque, Khanabad, Kunduz," the Mission said on Twitter. "Initial information indicates more than 100 people killed and injured in a suicide blast inside the mosque."
They added in a follow-up tweet: "Today’s incident is part of a disturbing pattern of violence: 3rd deadly attack this week apparently targeting a religious institution. Islamic State(KP) claimed responsibility for Sunday’s incident next to a Kabul mosque. Wednesday’s attack on a madrassa in Khost unclaimed."
The deputy police chief for Kunduz province, Dost Mohammad Obaida, told the Associated Press that most of the victims had been killed.
He believed the attack was the work of a suicide bomber who had mixed in with the crowd of worshipers inside the mosque.
“I assure our Shiite brothers that the Taliban are prepared to ensure their safety,” Obaida said.
The current reported death toll would be the largest since the US withdrawal from the country in August, during which the Taliban took over.
A series of deadly attacks against the Taliban have been carried out by the ISIS-K since it took control of Afghanistan.