Saturday's terrorist attack, which according to the locals, apparently targeted the Afghan security forces' convoy in Khost City, the provincial capital of Khost, also left six others injured including two children.
"We condemn this terrorist attack which took place in the first day of the holy Ramadan. We wish Allah’s mercy upon those who lost their lives, speedy recovery to the wounded, and convey our condolences to the brotherly Government and people of Afghanistan," Turkish Foreign Ministry said in a statement.
Afghan President Ashraf Ghani on Saturday said the attack invited the wrath of the people towards the Taliban.
"Terrorist groups that have no regard for religious values and blessed days, have once again committed a crime against humanity on the directives of their masters," Ghani said in a statement.
"Criminals must know that by killing and targeting innocent civilians, they cannot not reach their goals, but receive more hatred from the people," he added.
The High Peace Council, tasked with reaching a peace deal with the Taliban, termed the attack as "painful and very disturbing".
Mohammad Ismael Qasimyar, adviser at the HPC, told Anadolu Agency that such attacks were a setback to efforts for peace.
"We urge the Taliban to shun violence, and at least cease fire in the month of Ramadan," he said.
The attack was also widely condemned by the general public on social media, with one Tweeter asking "On the basis of what religion are you [Taliban] waging these atrocities?".
The first day of Ramadan is a public holiday in Afghanistan. In clear defiance to the call of the United Nations Assistance Mission in Afghanistan (UNAMA) for cease-fire in this holy month, the Taliban announced Friday they would in fact intensify their attacks during Ramadan.