However, a Taliban spokesman said the militants were conducting their own investigations to determine if any of the remaining hostages work for the Afghan government or security forces.
The incident comes despite President Ashraf Ghani's call for a cease-fire with the Taliban during the Muslim holiday of Eid al-Adha.
"I once again announce a ceasefire from tomorrow until the prophet's birthday provided that the Taliban reciprocate", said Ghani, referring to the Prophet Mohammed's birthday which Afghanistan celebrates on November 21.
A provincial council member in Kunduz said "a total of 300 to 400 passengers" could have been on the buses when the militants stopped them.
The buses, carrying passengers from Badakhshan and Takhar provinces, were on their way to the capital, Kabul, according to Abdul Rahman Aqtash, police chief of the Takhar province.
He said none of them were government employees or members of Afghanistan's security forces.
Security forces personnel on the buses will be kept in custody, the spokesperson added.
The anti-government armed militant groups including Taliban militants have not commented regarding the report so far.
"The United States and our worldwide partners support this initiative by the Afghan people and the Afghan government, and we call on the Taliban to participate". He reiterated the group's standing position that the country's 17-year war can only be brought to an end through direct talks with the United States.
Taliban sources said earlier that their leaders had provisionally agreed on a four-day truce, although supreme leader Sheikh Haibatullah Akhunzada still had to give his final approval.
"It is our hope, and that of the worldwide community, that the Afghan people may celebrate Eid al-Adha this year in peace, free from fear", he added, referring to the Islamic holiday that starts next week.
At least 150 soldiers and 95 civilians were killed in a five-day siege, which eased last week when Afghan soldiers backed by USA forces pushed back the heavily armed rebels. The heavy casualties underscore the challenges the government in Kabul faces since the US and North Atlantic Treaty Organisation officially ended their combat mission at the end of 2014.