Ten people working for mine-clearing organisation Halo Trust were shot dead in northern Afghanistan on Tuesday night.
Another 16 people were wounded in the attack on a demining camp in the Baghlan-e-Marzaki district in Baghlan province. A group entered the camp and opened fire, Halo said.
ISIS in Afghanistan claimed the attack, but the Afghan government blamed the Taliban.
"The Taliban entered a compound of a mine-clearing agency ... and started shooting everyone," interior ministry spokesman Tareq Arian said.
About 110 men from communities in northern Afghanistan were in the camp having finished their work on nearby minefields, Halo spokeswoman Louise Vaughan said.
"We strongly condemn the attack on our staff, who were carrying out humanitarian work to save lives. We are focused now on the care of the injured staff and supporting the families affected," the NGO said.
The incident happened in an area controlled by government forces, and the attackers were wearing masks, Baghlan governor's spokesman Jawed Basharat told AFP.
The wounded workers were treated at a hospital in Pul-e-Khumri City, in the centre of Baghlan, Afghanistan's Tolo News reported.
Taliban spokesman Zabihullah Mujahid denied responsibility for the attack.
Decades of conflict has left Afghanistan as one of the most heavily mined countries in the world.
Violence in the country has been on the increase since May when US and Nato forces began to withdraw from the country.
The US has already removed more than 50 per cent of its forces from Afghanistan, the Pentagon said on Tuesday.
After an order from President Joe Biden, the US military will remove 2,500 troops, 16,000 civilian contractors and hundreds of tonnes of equipment from Afghanistan by September 11, which marks the 20-year anniversary of the Al Qaeda attacks on New York and Washington.
In recent weeks, the Taliban made several advances on territory in Afghanistan as the group looks to capitalise on the security transition to expand its presence in the country.
In the past week, the Taliban gained control of a number of districts including two districts in the southern Zabul and Uruzgan provinces, the Shahrak district of Ghor province, and on Monday night, the group took the Dawlat Abad district in Faryab province.
Afghanistan television network Tolo News reported that 17 districts had fallen to the Taliban in the past two months.
Afghanistan says it has 300,000 security forces to ward off Taliban advances, but analysts suspect the number of active-duty forces is lower. Recent attacks by the Taliban killed dozens of security force members.
Peace negotiations that began in Doha last September between the Taliban and Afghan government have ground to a halt. The Taliban said they would not participate in the US-led mediations until all foreign troops had withdrawn from the country.