Officials said a suicide bomber attacked a crowd leaving a governor's compound in eastern Afghanistan, killing at least 18 people in the second such bombing in two days.
The June 17 bombing in the city of Jalalabad came as Afghans celebrated a three-day cease-fire marking the Eid al-Fitr holiday that ends the Muslim holy month of Ramadan.
Attaullah Khogyani, spokesperson for the provincial governor, told RFE/RL that 49 people were also wounded.
No one claimed responsibility for the attack, though suspicion fell on Islamic State militants, who were not included in the cease-fire between Taliban fighters and Afghan security forces.
Islamic State extremists claimed responsibility for a similar attack on June 16 in the Nangarhar region, in which at least 36 people were killed and 65 others wounded at a gathering of Taliban and government armed forces.
Nangarhar Province is the main base of IS militants in Afghanistan. The group has clashed with the Taliban in the past.
The suicide bomber in Jalalabad blew himself up at around the time President Ashraf Ghani announced an extension of the cease-fire with the Taliban and urged the militant group to extend its truce beyond June 20. Ghani's office on June 17 said the truce would be extended by another 10 days.
In a televised address, Ghani said he was prepared to discuss Taliban demands, including the status of foreign forces in the future.
"I order the security forces to remain on their defensive positions," Ghani said, adding that details of the extension would be released later.
A spokesman for the Afghan Taliban, however, said on June 17 that it has “no intention to extend” its truce.
Zabihullah Mujahid also said the group banned its fighters from attending public gatherings, going into cities, and meeting with the Afghan public, as well as officials and security forces, during the cease-fire.
In a statement, U.S. Secretary of State Mike Pompeo said Washington was ready to work with the Afghan government, the Taliban, and all the people of Afghanistan to reach a peace agreement and political settlement.
"The United States is prepared to support, facilitate, and participate in these discussions," Pompeo said in a statement.
The United Nations' mission in Afghanistan said it welcomed Ghani's announcement on extending the truce beyond Eid.
Earlier on June 16, dozens of unarmed Taliban entered the Afghan capital to celebrate Eid.
Videos and photos posted on news sites and social media showed soldiers and Taliban greeting and hugging each other and taking selfies in several provinces. Reuters reported that Afghan Interior Minister Wais Ahmad Barmak met Taliban fighters in the capital on June 15.
Despite more aggressive military operations against the Taliban under a new approach adopted by U.S. President Donald Trump last year, the Taliban still holds large swaths of the country.