MANSEHRA, Pakistan — Gunmen wearing military uniforms stopped a convoy of buses in northern Pakistan on Tuesday, ordered selected passengers to get off and then killed 16 of them in an apparent sectarian attack, the police and a lawmaker said.

The victims were Shiite Muslims, a minority in Pakistan that is frequently targeted by extremists from the majority Sunni community, said lawmaker Abdul Sattar. The gunmen spared several dozen other people in the four-bus convoy.

A spokesman for a faction of the Pakistani Taliban, a Sunni militant group, claimed responsibility for the killings.

The incident in the remote Kohistan region was the latest in a spasm of violence in the country in recent weeks that has demonstrated the resilience of militant networks, including al-Qaida allied groups. The U.S. has tried to support Pakistani security forces in the fight against the extremists, but relations between the two nations are strained, hampering cooperation.

The attack took place in the mountainous village of Harban Nala, which is some 211 miles (340 kilometers) north of the capital Islamabad. The area, part of the famed Silk Road linking northern Pakistan to China, is populated by Sunni tribes.