The attackers stopped three buses on a road and ordered the passengers out, shot dead nine of them and kidnapped the rest, said Massoum Hashemi, deputy police chief of Kunduz.
Government forces later freed most of the abducted passengers in a rescue operation.
The identity of the victims was not immediately clear.
"The Taliban have brutally killed nine civilians and taken about 20 with them," Hashemi said.
However, there was no claim of responsibility and Taliban spokesmen were not immediately available for comment. The Taliban have in the past denied accusations of attacks on civilians.
The brief capture by the Taliban of Kunduz last year was a major blow to the government of President Ashraf Ghani. The deterioration of security in the north has coincided with heavy fighting in the southern province of Helmand.
