At least 50 people were killed in an explosion at a mosque in Afghanistan’s Kunduz province on Friday, AFP reported.

There are differing reports about the number of casualties. The United Nations Assistance Mission in Afghanistan said more than 100 people had been killed or injured in the attack.

People from the minority Shia Muslim community pray at the mosque, according to Reuters.

“A suicide bomber managed to get into the Shia mosque by midday today [Friday] in Kunduz, detonated himself and this explains the high number of casualties,” Al Jazeera quoted its senior correspondent Hashem Ahelbarra as saying.

The Islamic State-Khorasan, an affiliate of the terrorist group ISIS in Afghanistan, has claimed responsibility for the attack, the BBC reported.

Relatives of those killed or injured in the attack gathered outside MSF Hospital in Kunduz city, AFP reported. “But armed Taliban guys are trying to prevent gatherings in case another explosion is planned,” an unidentified international aid worker said.

Kunduz province’s deputy police chief Dost Mohammad Obaida said an investigation into the attack is underway, Al Jazeera reported. “I assure our Shia brothers that the Taliban are prepared to ensure their safety,” he said.

The explosion in Kunduz took place five days after a blast outside the Eid Gah Mosque in Kabul, in which at least five people had been killed. The Islamic State-Khorasan had claimed responsibility for the attack, according to AFP.