A bombing at a mosque in the Afghan capital of Kabul during evening prayers killed at least 21 people, including a prominent cleric, and wounded at least 33 others, eyewitnesses and police said Thursday.

There was no immediate claim of responsibility for the attack on Wednesday night, the latest to strike the country in the year since the Taliban seized power. Several children were reported to be among the wounded.

The Islamic State group’s local affiliate has stepped up attacks against the Taliban and civilians since the former insurgents took over the country last year as U.S. and NATO troops were in the final stages of their withdrawal. Last week, the extremists claimed responsibility for killing a prominent Taliban cleric at his religious center in Kabul.

The mosque bombing comes just two days after the anniversary of the fall of Kabul on Aug. 15, 2021.

Khalid Zadran, the spokesman for Kabul’s Taliban police chief, gave the latest figures to The Associated Press for the bombing at the Siddiquiya mosque in the city’s Kher Khanna neighborhood. An eyewitness told the AP the explosion was carried out by a suicide bomber.

The slain cleric was Mullah Amir Mohammad Kabuli, the eyewitness said, speaking on condition of anonymity because he was not authorized to talk to the media.

Taliban spokesman Zabihullah Mujahid condemned the explosion and vowed that the “perpetrators of such crimes will soon be brought to justice and will be punished.”

There were fears the casualty numbers could rise further. On Thursday morning, one witness to the blast who gave his name as Qyaamuddin told the AP he believed as many as 25 people may have been killed in the blast.

“It was evening prayer time, and I was attending the prayer with others, when the explosion happened,” Qyaamuddin said. Some Afghans go by a single name.

AP journalists could see the blue-roofed, Sunni mosque from a nearby hillside. The Taliban parked police trucks and other vehicles at the mosque, while several men carried out one casket for a victim of the attack.

During their previous, 1996-2001 rule of Afghanistan, the Taliban imposed their harsh interpretation of Islamic laws, severely restricting individual freedoms and especially the rights of women. A U.S.-led invasion toppled the Taliban, who had also hosted al-Qaida leader Osama bin Laden, following the Sept. 11, 2001 terrorist attacks in the United States.

Since regaining power, the former insurgents have faced a crippling economic crisis as the international community, which does not recognize the Taliban government, froze funding to the country. On Thursday, the Taliban hosted a gathering of 3,000 tribal elders, religious scholars and others in Kandahar, their state-run Bakhtar News Agency reported. It wasn’t immediately clear what topics they planned to discuss.

Since sweeping to power in August 2021, the Taliban have been battling the surging Islamic State affiliate known as Islamic State in Khorasan Province or IS-K, which is proving to be an intractable security challenge for Afghanistan’s Taliban-run government.

The group has attracted many militants to its violent and extreme ideology, including promises of a caliphate to unite the Islamic world — a goal never espoused by the Taliban. Also, IS calls for a worldwide jihad, or holy war, against non-Muslims, while the Taliban have confined their struggle to Afghanistan.

In another development, the Taliban confirmed on Wednesday that they had captured and killed Mehdi Mujahid in western Herat province as he was trying to cross the border into Iran.

Mujahid was a former Taliban commander in the district of Balkhab in northern Sar-e-Pul province, and a rare member of the minority Shiite Hazara community among the Taliban ranks.

Mujahid had turned against the Taliban over the past year, after opposing decisions made by Taliban leaders in Kabul.