Afghan President Ashraf Ghani has condemned as "barbaric" an attack on a wedding party in Kabul that killed at least 63 people and left 182 others injured and called an extraordinary security meeting to discuss ways to avoid such "lapses."
The radical militant group Islamic State (IS) has claimed responsibility for the attack, although it has falsely asserted connections to bombings in the past and Afghan officials were initially silent on IS's possible role.
The suspected suicide bombing, on a huge wedding reception at a hotel in western Kabul, was the deadliest attack in Kabul this year and came with Washington and the fundamentalist Taliban reportedly nearing a deal to end a nearly 18-year war.
WATCH: Wedding Party Hit In One Of Kabul's Deadliest Bombings
"I strongly condemn the inhumane attack on the wedding hall in Kabul last night," Ghani said in a tweet. "My top priority for now is to reach out to the families of victims of this barbaric attack. On behalf of the nation, I send my heartfelt condolences to the families of those who were martyred."
The Afghan president also tweeted, "In response to this targeted attack I have called an extraordinary security meeting to review and prevent such security lapses."
The UN secretary-general's special representative for Afghanistan, Tadamichi Yamamoto, described the bombing as a “cowardly act of terror."
“I condemn these deliberate attacks on civilians that signal a deliberate intent to spread fear among the population, which has already suffered too much,” Yamamoto, who also heads the United Nations Assistance Mission in Afghanistan (UNAMA), said in a statement.
U.S. peace envoy Zalmay Khalilzad took to Twitter to condemn the "heinous attack."
"We must accelerate the Afghan Peace Process including intra-Afghan negotiations. Success here will put Afghans in a much stronger position to defeat" the IS group, he wrote in a separate tweet.
The Taliban had denied responsibility for the blast and condemned it as "forbidden and unjustifiable."
But Ghani said that group at least shares blame.
"Taliban cannot absolve themselves of blame, for they provide platform for terrorists," Ghani tweeted, adding a declaration of a period of mourning.
Later, multiple reports said IS or an IS affiliate in Afghanistan had issued a statement saying it carried out the attack to target "heretics."
It reportedly said a suicide bomber struck the "large gathering" while other fighters "detonated a parked explosives-laden vehicle" once security forces arrived.
The bombing hit a district of the Afghan capital more populated by Shi'ites than many other parts of the city.
IS and its sympathizers and affiliates have repeatedly targeted Shi'a in addition to other victims since they became active in Afghanistan in 2015.
Interior Ministry spokesman Nasrat Rahimi said women and children were among the wounded after the bomb struck at the Dubai City wedding hall on Kabul’s west side.
“Unfortunately, the blast caused civilian casualties,” he said.
"Around 1,200 guests were invited to the wedding," Ahmad Omid, a survivor who said the gathering was for his father's cousin, told AP. "I was with the groom in the other room when we heard the blast and then I couldn't find anyone. Everyone was lying all around the hall."
Weddings in Kabul’s big wedding halls are considered centers of community life that offer a brief respite from decades of war.
The explosion came a few days after the Eid al-Adha holiday ended and just before Afghanistan marks 100 years of independence.
On August 7, a car bomb exploded in the same section of Kabul, killing 14 people and wounding 145, mostly women, children, and other civilians.
Afghan security forces were said to have been the intended target in that attack.
Early on August 18, at least 10 civilians were said to have died when a roadside bomb struck a vehicle in the Dawlat Abad district of the northern Balkh Province, near the border with Turkmenistan, dpa reported, citing an Afghan police spokesman.
More than 3,800 civilians were killed or injured during the first six months of this year alone, according to UNAMA.
On August 16, the Afghan Taliban leader’s brother was killed in Pakistan from a bomb explosion inside a mosque.
Taliban leader Haibatullah Akhundzada was not in the mosque when the bomb went off but his younger brother, Hafiz Ahmadullah, was among those killed, according to Afghan Islamic Press and Reuters.
"If someone thinks martyring our leaders would stop us from our goal they're living in a fool's paradise," a senior Taliban leader told Reuters by telephone from an undisclosed location on August 17.
"We are close to our goals,” the Taliban figure said, referring to the talks with the United States.
The Afghan war -- which ousted a mostly unrecognized Taliban government after that fundamentalist group's allies from Al-Qaeda carried out the deadliest terrorist attack ever on U.S. soil on September 11, 2001 -- is the longest conflict in U.S. history.