Two bomb blasts apparently targeting Shia Muslim shrines as hundreds of people gathered to mark the day of Ashoura have killed at least 60 people and injured scores more.
At least 56 people were killed by a suicide bomber who detonated explosives at the gate of the Abu-Ul Fazil shrine in the capital Kabul on Tuesday, many of them children, Afghan officials said.
Al Jazeera's Jennifer Glasse, reporting from the blast site in Kabul, said police had confirmed the death toll. The ministry of health said that more than 100 people were injured in the attack.
Ambulances rushed to the scene to take the wounded to hospital while some berated police for allowing the attack to occur on a major religious holiday, our correspondent said.
"I was there watching people mourning when there was suddenly a huge explosion," witness Ahmad Fawad said.
"Some people around me fell down injurefd. I wasn't hurt, so I got up and started running. It was horrible," he said.
"No Shia group has the arms, organisation or experience to indulge in sectarian violence based on suicide attacks"
- Ahmad Shuja,
Director of Foundation for Afghanistan
In a separate attack, a bicycle bomb near a mosque in the northern city of Mazar-e-Sharif killed four worshippers, a district police chief said.
The Taliban condemned both attacks as the brutal work of "enemies", a spokesperson for the armed group said.
"Very sadly we heard that there were explosions in Kabul and Mazar-e-Sharif, where people were killed by the enemy's un-Islamic and inhuman activity," Zabihullah Mujahid said in a statement published on the group's website.
Ahmad Shuja, an Afghan blogger and commentator, based in Washington, told Al Jazeera the attacks were unlikely to lead to sustained sectarian violence.
"No Shia group has the arms, organisation or experience to indulge in sectarian violence based on suicide attacks. They have been disarmed by the Disarmament, Demobilisation, and Reintegration (DDR) process and Disbandment of Illegal Armed Groups (DIAG) in Afghanistan [as a result they] have been fairly successful of stripping every one of their arms," said Shuja.
"It's important to consider that Iran, Pakistan, and Saudi Arabia have in the past supported various Shia and Sunni sectarian groups and could potentially fill that void now."
Karzai flies home
Afghan President Hamid Karzai, who was in Germany for the Bonn conference on Afghanistan earlier this week, cancelled a visit to the UK to return to Afghanistan after the deadly attacks.
Earlier he spoke of the unprecedented nature of the attack, saying it was the first time "terrorism of that horrible nature" had taken place on such an important public holiday.
The blasts occurred as Shias gathered to carry out religious rituals to mark one of the most significant days in their calendar.
Ashoura, a public holiday in Afghanistan, is marked by Muslims as a whole, but for Shia Muslims it is a major religious festival which commemorates the martyrdom of Imam Hussein, a grandson of the Prophet Muhammad.
Shias were banned from marking Ashoura in public under the Taliban. This year, there are more Ashoura monuments around the city than in recent years, including black shrines and flags.
Karzai also appealed to Afghanistan's neighbour Pakistan, which boycotted the Bonn meeting, saying it had "a very important role to play in the peace process in Afghanistan".
At Monday's conference, delegates pledged sustained support for Afghanistan for another decade, in exchange for clear progress on good governance.
Pakistan and the Taliban - both seen as pivotal to any end to the fighting in Afghanistan - decided to not attend the talks, undermining already modest hopes for real progress.
Kabul has been targeted by a series of bold attacks in recent months; include assaults on the US embassy, a major hotel and the offices of the British Council.
Meanwhile, a bomb placed in a motorcycle exploded in the southern Afghan city of Kandahar on Tuesday afternoon, injuring three civilians, a spokesmfan for the provincial governor said.
The site of the Kandahar blast was not near any mosque or shrine.