A grenade blast inside a mosque in a heavily populated district of Kabul, Afghanistan’s capital, injured at least six people, authorities said, just minutes after worshippers offered midday prayers.

Since the Taliban took power in August of last year, attacks on public targets have decreased significantly, but ISIL (ISIS) affiliates continue to operate in sections of the destabilized country.

“We had concluded our prayers and were about to leave the mosque when the blast happened,” said Mohammed Yasin, a worshipper.

A grenade was thrown into the Pul-e-Khisti mosque, according to Kabul police spokesman Khalid Zadran, and a suspect was captured at the site. The mosque is in a heavily populated district of Kabul, surrounded by bustling businesses, markets and restaurants.

Although no group has claimed responsibility, recent attacks in Kabul and other places have been carried out by the Islamic State of Khorasan Province (ISKP, ISIS-K).

The ISKP claimed responsibility for the November attack on a military hospital in Kabul, which left 19 people dead. The group also claimed responsibility for a suicide attack on a Shia mosque in Kandahar in October, which killed at least 60 people.

Taliban authorities claim that their forces have defeated the group, but observers say the ISKP poses a significant security threat to Afghanistan’s new rulers.

The US offered up to $10 million in February for information leading to the location or identification of Sanaullah Ghafari, the leader of ISKP, ISIL’s Afghan offshoot.

In a separate attack on Sunday, an explosion at the country’s largest money changing market, Sarai Shahzada – not far from the attacked mosque — killed at least one person and injured 59 others.