KABUL, Afghanistan — A day after a lethal Taliban assault on an army base in northern Afghanistan, an official said on Saturday that at least 140 soldiers had been killed, making it the single deadliest known attack on an Afghan military base in the course of the long war.
“Today, there was even a shortage of coffins,” said the official, Ibrahim Khairandish, a member of the provincial council in Balkh Province, where the attack occurred. Citing information from army officials, Mr. Khairandish said 60 soldiers had also been wounded in the attack.
The soldiers, most of them unarmed, were shot while eating lunch or emerging from a Friday Prayer service at the headquarters of the Afghan Army’s 209th Corps in Balkh by assailants in military uniforms who entered after another attacker had detonated explosives at a check post. The Taliban claimed responsibility for the assault.
“Most of those killed were in the mosque; some of them were in the dining facility,” Mr. Khairandish said.
Details were still emerging on Saturday, but other officials said the death toll had been staggeringly high.
Another Balkh official, who spoke on the condition of anonymity because he was not authorized to speak to the news media, said 137 soldiers had been killed. A Western military official in Kabul, who insisted on anonymity because of a policy against commenting on Afghan security forces’ casualty figures, put the death toll at more than 100.
Gen. Dawlat Waziri, a spokesman for the Afghan Ministry of Defense, said on Saturday that “more than a hundred soldiers were killed and wounded” in the attack, but he declined to discuss precise numbers.
“In continuing with their barbarism and criminality, the Taliban carried out a group attack in the 209th Corps mosque when our soldiers were standing for group prayers,” General Waziri said. “This was against all human and Islamic values.”
Among the dead was Qari Ahmad Khan, 22, who had joined the army after completing his studies at an Islamic school, where he specialized in memorizing the Quran, said his brother, Mohamed Khan, 43. Mr. Khan said he waited for hours near the base before army officials released his brother’s body.
“The army corps was not allowing anyone in — not even 100 meters close to the base,” Mr. Khan said. “Tens of people were waiting there, crying and wailing. Some were searching for the bodies of their martyrs, others didn’t know whether the person they were waiting for was dead or wounded.”
President Ashraf Ghani arrived in Balkh Province on Saturday to visit the army base.
The Taliban released the names and a picture of 10 men who they said had taken part in the assault. All were dressed in Afghan military uniforms, down to helmets and kneepads. A Taliban spokesman, Zabihullah Mujahid, said the assailants had been led inside the base by four soldiers who had long been working for the militants.
The attack came weeks after militants entered the Afghan Army’s main hospital in Kabul, the capital, and killed more than 50 people in a siege that lasted nearly seven hours. The Islamic State, also known as ISIS or ISIL, claimed responsibility for that assault. The militants had inside help in that attack, security officials said.
While the Islamic State has been getting attention in recent days because of the American military’s use of its largest conventional bomb against the group’s cave complex in eastern Afghanistan, the Taliban remain the biggest security threat to the country. The Taliban have expanded their territory over the past couple years and threaten several cities.
Such a major security breach in Balkh, even before the start of the insurgents’ spring offensive, is a major concern to Afghan forces who are already struggling in the fight against the Taliban.
In 2016, more than 6,700 Afghan service members were killed in battle. The repeated ability of a few militants to cause tremendous bloodshed in highly secure areas was an especially troubling sign.
Jawad Sukhanyar and Zahra Nader contributed reporting