A Taliban official stated that at least five civilians died in the bomb blast outside a Kabul mosque on Sunday. This was the most serious attack on the Afghan capital since the departure of U.S. forces at the end August. Although there was no immediate claim of responsibility for the attack, suspicion fell upon Islamic State extremists, who have intensified attacks against the Taliban in recent weeks in particular in an IS stronghold east of Afghanistan.

A roadside bomb was apparently set off at the Eid Gah Mosque’s gate in Kabul, just as a memorial service was taking place for Zabihullah Mujahid, the chief Taliban spokesperson. Qari Saeed Khosti, spokesperson for the Interior Ministry, stated that five people were killed. The Taliban are facing increasing challenges just weeks after taking control of Afghanistan in a blitz operation that culminated in their takeover in Kabul on August 15. The Taliban had been involved in bombing and shooting attacks during their 20-year-old insurgency. Now they must contend with rival militants who use the same tactics. As the Taliban attempt to manage the country without the huge amount of foreign aid they received from the U.S., the security issues are increasing at a time when the economy is in crisis.

According to a Taliban spokesperson, Bilal Karimi, three suspects were detained in Sunday’s blast in Kabul. He stated that the Taliban fighters had not been hurt. Mohammad Israil, Kabul resident said he heard a “loud sound” and saw people fleeing. A Kabul-based emergency hospital, funded by Italy, tweeted that it had treated four victims of the blast. Taliban security forces surrounded the mosque and kept it secure. Later that afternoon, the site was cleaned. The entrance gate’s ornamental arch sustained minor damage. Since their mid-August overthrow, IS militants have intensified attacks on the Taliban, signaling an increasing conflict between them.

IS has claimed responsibility in several murders at Jalalabad, the provincial capital, in eastern Nangarhar. Late August saw an IS suicide bomber attack Kabul’s international airport. It was the deadliest attack in Afghanistan in recent years, killing 169 Afghans and 13 U.S. military personnel. Although attacks in Kabul are rare, IS has been showing signs that it is expanding its reach beyond the east and moving closer to the capital. Taliban fighters attacked an IS hideout in Parwan province, just north of Kabul. Four Taliban fighters were injured in the raid by an IS roadside bomb.