Rebel separatists killed 14 people, including three security personnel, after stopping vehicles at a fake checkpoint in Pakistan's volatile southwest on Tuesday, officials said.
The attack appears to have mainly targeted people originally from the central province of Punjab working in Baluchistan, ahead of the Eid al-Fitr holiday that marks the end of Ramadan.
Separatist rebels have been fighting in Baluchistan since 2004, demanding political autonomy and a greater share of profits from the region's natural oil, gas and mineral resources.
The gunmen, dressed in the uniform of Pakistani security forces, carried out Tuesday's attack in the Mach area of Bolan district, 70 kilometres (44 miles) southeast of the provincial capital Quetta.
"Miscreants blocked the road in two places. First they took away five FC (paramilitary) men from an FC patrol vehicle, tied them up and snatched their walkie-talkies and weapons," provincial home secretary Akbar Hussain Durrani told AFP.
The rebels then stopped two buses and took away 13 labourers. Security force personnel chased after them, but the rebels fired off a rocket that killed one security officer, Durrani said.
"Then they lined them up in the mountains and killed 13," added Durrani.
Local official Kashif Nabi confirmed the incident and said the bodies had been recovered.
"We are making arrangements to bring them to Quetta," he said.
Asked whether Baluch rebels were responsible for the attack, Durrani told AFP: "Definitely they are."
Baluchistan is also a flashpoint for surging sectarian violence between Pakistan's majority Sunni Muslims and Shiites, who account for around a fifth of the country's 180 million people.
It is one of the most deprived areas of Pakistan.