Kabul: A national day of mourning was declared in Afghanistan for Sunday, a day after 80 people were killed and an estimated 231 others were wounded by a bomb attack in Kabul.
Two attackers detonated their suicide vests among a crowd of protesters, while another was killed by security forces.
Islamic State claimed responsibility via its mouthpiece Aamaq News Agency.
President Ashraf Ghani vowed to "avenge the blood of our loved ones," and ordered the flag to fly at half-mast at all government buildings in Afghanistan and abroad.
At least 10,000 people were taking part in Saturday's protest, according to event organizer Mohammad Arif Rahmani.
They were demanding that a new power cable being laid from Turkmenistan to Pakistan via Kabul be rerouted through the province of Bamyan, currently not connected the electricity grid.
The government has rejected the demands, citing further delays and added costs.
The Interior Ministry announced a nationwide 10-day ban on protests due to security reasons after the attack.