An explosion in eastern Afghanistan near the border with Pakistan on Monday killed nine children and wounded four, according to the office of a Taliban-appointed governor. A statement from the governor’s office said the blast happened when a cart selling food items struck an old, unexploded mortar shell in the district of Lalopar, in eastern Nangarhar province.

No other details were immediately available.

The province has been a stronghold for the offshoot of ISIS known as ISIS-K, the terrorist group that claimed responsibility for last year’s attack in Kabul that killed 13 U.S. service members and at least 170 Afghans.

The Taliban rival has staged several attacks targeting Afghanistan’s new rulers since the Taliban took over the country in mid-August. ISIS has operated in Afghanistan since 2014, carrying out dozens of horrific attacks and most often targeting the country’s minority Shiite Muslims.

Afghanistan is among the countries with the most unexploded land mines and other ordnance from the country’s decades of war and conflict. When the ordnance detonates, the victims are often children.