KABUL, Afghanistan (AFP) — Islamic State group jihadists claimed responsibility for twin explosions Saturday that ripped through crowds of Shiite Hazaras in Kabul, killing at least 64 people and wounding 265 others in their first major attack in the Afghan capital.

The bombings, apparently aimed at sowing sectarian discord in a country well known for Shia-Sunni harmony, came as thousands of Hazaras gathered to protest over a multi-million-dollar power line.

The scene of the attack was littered with charred bodies and dismembered limbs, with ambulances struggling to reach the scene as authorities had overnight blocked key intersections with stacked shipping containers to control movement of the protesters.

“The death toll has jumped to 64 and 265 others have been wounded,” health ministry spokesman Mohammad Ismail Kawoosi said, adding that the toll could rise further.

The wounded overwhelmed city hospitals, officials said, with reports emerging of blood shortages and urgent appeals for donors circulating on social media.

The Taliban, who are in the middle of their annual summer offensive and are more powerful than IS, strongly denied any involvement in the attack.

IS claimed the bombings in a statement carried by its affiliated Amaq news agency, calling it an attack on Shiites.

“Two fighters of the Islamic State detonated their explosive belts in a gathering of Shiites in… Kabul,” Amaq said.

The attack represents a major escalation for the group, which so has largely been confined to the eastern province of Nangarhar.

The National Directorate of Security, Afghanistan’s main intelligence agency, said the attack was masterminded by Abu Ali, an IS commander in Nangarhar’s volatile Achin district.

“Three IS militants were involved in the attack. The third attacker was gunned down by security officials,” an NDS official said.

The attack came as thousands of demonstrators gathered to demand that a multi-million-dollar power line pass through their electricity-starved province of Bamiyan, one of the most deprived areas of Afghanistan with a large Hazara population.

“The horrific attack on a group of peaceful protestors in Kabul demonstrates the utter disregard that armed groups have for human life,” Amnesty International said in a statement.

“Such attacks are a reminder that the conflict in Afghanistan is not winding down, as some believe, but escalating, with consequences for the human rights situation in the country that should alarm us all.”