An explosion ripped through an area in Kabul on Saturday where hundreds of minority Shiite Hazaras had gathered to protest over a key power transmission line, police said.

The death toll from powerful twin explosions that ripped through crowds of protesters in Kabul Saturday has jumped to 80, while 231 have been injured, the health ministry said, according to AP. The toll could rise further.

#UPDATE 80 dead as IS group claims twin blasts during Kabul protest https://t.co/8iwXrsT4cQ #KabulBlast — AFP news agency (@AFP) July 23, 2016

Afghan President Ashraf Ghani has declared Sunday a day of national mourning, stating the state will take strict action against those responsible. "I promise you I will take revenge against the culprits. I have ordered the attorney general to set up a commission to investigate this incident," Ghani said in a television address on Saturday, as reported by AP.

A powerful explosion on Saturday ripped through crowds of minority Shiite Hazaras in Kabul who had gathered to protest over a power line.

According to reports, Islamic state has claimed responsibility for the attacks however an official statement is yet to come.

#BREAKING IS group claims attack on Kabul Shiite protest: IS-linked agency — AFP news agency (@AFP) July 23, 2016

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

It appears to be the single deadliest attack in Kabul to be claimed by IS jihadists, who are making steady inroads in the country, challenging the Taliban on their own turf.

The bombings aimed at targeting a minority sect could deepen sectarian divisions in a country well known for communal harmony despite decades of war.

Reacting to the attack, Afghan President Ashraf Ghani said he was "deeply saddened" by the carnage, adding that the casualties included security officials.

"Holding protests is the right of every citizen of Afghanistan and the government puts all efforts to provide security for the protestors, but terrorists entered the protests, and carried out explosions that martyred and wounded a number of citizens including members of security forces," the presidential palace said.

The Indian Prime Minister, Narendra Modi has condemned the attacks on innocent civilians in Afghanistan and has offered his condolence for the lives lost.

Strongly condemn dastardly terror attack on innocent civilians in Kabul. Sincerely condole loss of lives & injuries in senseless violence. — Narendra Modi (@narendramodi) July 23, 2016

India stands with Afghanistan in resolutely opposing all forms of terrorism. — Narendra Modi (@narendramodi) July 23, 2016

Amnesty International has also deeply condemned the blasts.

"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."

The scene of the blast 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 impede movement of the protesters.

Eyewitness Ramin Anwari described seeing up to eight bodies in the Demazang area, where protesters were preparing to set up a camp after a four-hour march. He had no further details.

One of the march organizers Laila Mohammadi said she arrived at the scene soon after the blast and saw "many dead and wounded people."

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

Thousands of demonstrators had 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 protest march was largely peaceful before the explosion struck as the demonstrators sought to march on the presidential palace, waving flags and chanting slogans such as "death to discrimination".

The 500-kilovolt TUTAP power line, which would connect the Central Asian nations of Turkmenistan, Uzbekistan and Tajikistan with electricity-hungry Afghanistan and Pakistan, was originally set to pass through the central province. But the government re-routed it through the mountainous Salang pass north of Kabul, saying the shorter route would speed up the project and save millions of dollars. Hazara leaders in the ethnically divided nation lashed out at the Pashtun president, calling the decision prejudiced against the Hazaras, a community that has suffered a long history of oppression.

Main roads across the Afghan capital Kabul were blocked by the authorities as thousands of ethnic Hazaras marched through the city demanding a planned power line be rerouted through their poverty-stricken province.

Police moved trucks and containers into the city overnight yesterday to block roads and prevent marchers reaching the city center or the presidential palace. Shops and other businesses were forced to close and movement around the city of 4.5 million people was severely restricted.

It was the second march held by members of the Hazara minority against the current route of a multi-million-dollar regional electricity line. The last one in May attracted tens of thousands of people, also shutting down the central business district.

Saturday's protest follows a similar demonstration in May, which drew tens of thousands of people. The three million-strong Hazara community has been persecuted for decades, with thousands killed in the late 1990s by Al-Qaeda and the mainly Pashtun Sunni Taliban.

With inputs from agencies