A bombing wounded or killed at least 100 people at a mosque full of Shiite Muslim worshippers in Afghanistan. The blast occurred in Kunduz, the capital of Kunduz province during the Friday noon prayer, which is the highlight of the Muslim religious week when mosques are the most crowded.

Thus far there has been no immediate claim of responsibility, “but militants from the Islamic State groups have a long history of attacking Afghanistan’s Shiite minority” reports the Associated Press.

A Taliban police official said at least 100 were injured or killed, and the deputy police chief for Kunduz province said majority of the victims “have been killed.” The chief also said the attack may have been a suicide bomber who had mixed in the worshippers in the mosque.

“I assure our Shiite brothers that the Taliban are prepared to ensure their safety” said the police chief, Dost Mohammad Obaida who also said an investigation was underway.

CharlieKirk.com reported this week that the Taliban was responsible for letting the ISIS-K member free from prison just days before they carried out the suicide attack at the Kabul international airport. The attack killed at least 169 Afghans and 13 American servicemen and women.

The AP reports “if confirmed, a death toll of dozens would be the highest since U.S. and NATO forces left Afghanistan at the end of August and the Taliban took control of the country.” Additionally, “the Taliban leadership has been grappling with a growing threat from the local Islamic State affiliate, known as the Islamic State in Khorasan” adds the AP.

IS have ramped up attacks and has declared war on Shiite Muslims, Afghanistan’s minority. ”Previously, IS had claimed a bombing on Sunday outside Kabul’s Eid Gah Mosque that killed at least five civilians Another attack on a madrassa, a religious school, in Khost province on Wednesday was not claimed” reports the AP.