An explosion tore through a crowded mosque in western Afghanistan on Friday, killing at least 18 people, including a prominent cleric, Taliban officials and a local medic said. At least 21 people were hurt.

The blast went off in the Guzargah Mosque in the western city of Herat during Friday noon prayers, the highlight of the Muslim religious week when places of worship are particularly crowded.

The explosion killed Mujib-ul Rahman Ansari, a prominent cleric who was known across Afghanistan for his criticism of the country’s Western-backed governments over the past two decades. Ansari was seen as close to the Taliban.

His death was confirmed by the chief Taliban spokesman, Zabihullah Mujahid.

Ambulances transported 18 bodies and 21 wounded people from the blast to hospitals in Herat, said Mohammad Daud Mohammadi, an official at the Herat ambulance centre.

There was no immediate claim of responsibility for Friday’s blast.