Kabul, Afghanistan (CNN) As onlookers lauded reports of Taliban fighters and Afghan government security forces shaking hands and embracing during an unprecedented ceasefire to mark Eid, a deadly bombing in eastern Afghanistan marred celebrations Saturday.

The Afghan Taliban called last week for its fighters to observe a three-day truce -- except against foreign forces -- to coincide with a 10-day ceasefire declared by the Afghan government for Eid al-Fitr , the holiday marking the end of the Muslim holy month of Ramadan.

Purported Taliban militants and Afghans embrace Saturday in Ghazni during a three-day truce for Eid.

Afghan journalists, students and diplomats have all reported witnessing the unusual scenes of reconciliation via Twitter over the past two days. Photos and videos purported to show handshakes and hugs in many parts of the country.

However, the mood of optimism was overshadowed by a blast Saturday in the eastern Nangarhar province, with both Taliban and civilians among at least 25 people killed and 54 wounded, according to Ataullah Khogyani, Nangarhar provincial spokesman.

The explosion occurred about 5:15 p.m. (8:45 a.m. ET) at a gathering of Taliban and Afghan civilians in the province's Rodat district, Khogyani said. The wounded were taken to hospitals for treatment, he said.

ISIS claimed responsibility for the attack in a statement from Amaq News Agency, the terrorist group's media wing.

"A suicide attack struck a gathering of Afghan forces and Taliban movement in the city of Jalal Abbad in Nangarhar," the statement said.

US Army Lt. Colonel Martin O'Donnell, spokesman for US forces in Afghanistan, had earlier attributed the blast to ISIS-Khorasan, the group's affiliate in the country.

"We offer our deepest condolences to the families of those martyred and all those whose joyous celebration was impacted by this attack on peace, which ISIS-K claimed," O'Donnell said in a statement.

"This violence will not halt the peaceful gatherings in Nangarhar and around the country celebrating a long overdue cessation of hostilities and a chance for lasting peace, or undermine the strength and resolve of the Afghan people and the international commitment to Afghanistan," he added.

Afghan and US forces launched a counteroffensive against the ISIS affiliate in March 2017 with the aim of driving it out of Afghanistan.

Embraces during ceasefire

Afghan diplomat Zardasht Shams on Friday tweeted, "Interesting images from across Afghanistan on the eve of Eid Day #ceasefire Afghan Army & Taliban hugging each other. May this ceasefire sustains forever."

Interesting images from across Afghanistan on the eve of Eid Day #ceasefire Afghan Army & Taliban hugging each other. May this ceasefire sustains forever. Ameen pic.twitter.com/5Osg3R2PYg — Zardasht Shams 🇦🇫 (@shamszardasht) June 15, 2018

CNN cannot independently verify those images, but a freelance journalist confirmed he saw similar scenes in Logar province on Friday and Saturday.

Abdulhaq Omeri, a correspondent with Afghanistan's TOLO News, tweeted photos of what appeared to be Taliban fighters and security forces posing together.

Kabul city police spokesman Hashmat Stanikzai told CNN on Saturday that a number of unarmed Taliban had entered the Afghan capital from other police district areas. They handed over their weapons at the entrance, with their weapons to be given them back when they left the city, he said.

In another rare piece of good news, Afghanistan's cricket team made its Test match debut Thursday against India.

Ghani: Chance to move forward

Afghan President Ashraf Ghani tweeted last weekend that he was pleased the Taliban had accepted the ceasefire declaration for Eid.

"This is the first break in 23 years and we ask for your support to utilize the window for moving forward with intra-Afghan peace talks," he said.

US forces in Afghanistan also said they would respect the ceasefire with the Taliban. The truce does not include US counterterrorism efforts against groups such as al Qaeda and ISIS.

Afghan government officials confirmed this week that Pakistan Taliban leader Mullah Fazlullah had been killed in a US drone strike in Afghanistan.

US Secretary of State Mike Pompeo said Saturday that the United States supports a move by the Afghan leader to extend the ceasefire.

"As President Ghani emphasized in his statement to the Afghan people, peace talks by necessity would include a discussion of the role of international actors and forces," Pompeo said in a statement. "The United States is prepared to support, facilitate, and participate in these discussions."

Years of bitter fight

Afghanistan has suffered a recent uptick in violence despite reports in March that suggested some factions of the Taliban had expressed interest in pursuing peace talks with the Afghan government.

Ghani first spoke about the possibility of a ceasefire with the militant Islamist group in February when he announced the Afghan government was willing to recognize the Taliban as a legitimate political party as part of a potential agreement.

"We're ready to restart talks about peace with Pakistan again and forget bitter experiences of the past and start a new chapter," he said.

The Taliban has been waging a bitter fight in Afghanistan, with the ultimate goal of ruling the country and imposing its strict interpretation of Islamic law. The group controlled Afghanistan until its 2001 ouster by the US-led coalition that invaded following the 9/11 attacks.

In recent years, a resurgent Taliban has taken control of significant swaths of the country and terrorized Afghans and foreigners alike. Brazen terrorist attacks have even shaken the resolve of those who live in the heavily secured capital, Kabul, and raised questions over the Afghan government's ability to protect the country.