Reacting to four explosions Thursday in Afghanistan, Iran’s Foreign Ministry spokesman Saeed Khatibzadeh expressed concern over a rising number of “bitter incidents.”

In the northern Afghan city of Mazar-i-Sharif, a bomb killed at least 20 worshippers in the Seh Dokan Shiite mosque, in the second major attack on Afghanistan’s Shiite community, mostly Hazara, in a week. The Islamic State group (Isis/Daesh) claimed responsibility. Fifty-eight people were injured, 32 seriously.

Hazaras – who are an ethnic and religious minority making up around 20 percent of Afghanistan’s population – have been frequently targeted by Sunni extremists who regard them as heretics. The Mazar-i-Sharif bombing came two days after blasts tore through a Shiite high school in western Kabul, killing at least six people and wounding 11.

There was some confusion over whether Isis-Daesh claimed responsibility for a second explosion Thursday near a police station in Kunduz that killed four and injured 18.

In a third attack, a Taliban vehicle was hit by a roadside mine in eastern Nangarhar province, killing four Taliban members and wounding a fifth. The fourth explosion, caused by a mine planted in the Niaz Beyk area of Kabul, wounded two children.

Like other Afghan neighbors, Iran has not formally recognized the Taliban authorities that took over when the United States last summer ended its 20-year military presence. Tehran has called for a broad-based government.