There was no immediate claim of responsibility, but Baloch separatists have figured in similar past killings of those identified as hailing from the eastern province of Punjab.
Government official Naveed Alam said the bodies with bullet wounds were found in the mountains overnight, while a provincial government spokesman, Shahid Rind, said the passengers were seized from two buses on Thursday evening.
"We are identifying the bodies and reaching out to their families," he said, adding the victims, working as labourers in the restive region, were returning home to Punjab.
Ethnic insurgents accuse Pakistan's government of stealing regional resources to fund expenditure elsewhere, mainly in the sprawling province of Punjab.
Security forces foiled three insurgent attacks on Thursday before the kidnappings, Rind said, accusing neighbour and arch rival India of backing the militants.
The Indian foreign ministry did not immediately respond to a Reuters request for comment.
New Delhi denies accusations by Islamabad that it is funding, training and backing the militants in a bid to stoke instability in the region, where Pakistan relies on China among international investors to develop mines and mineral processing.
"India is now doubling down to further its nefarious agenda through its proxies," the Pakistani army said in a statement in remarks that followed the worst fighting in nearly three decades between the nuclear-armed foes in May.
The Baloch Liberation Army (BLA) is the strongest among the insurgent groups long operating in the area bordering Afghanistan and Iran, a mineral-rich region.
In recent months, separatists have stepped up their attacks, mostly targeting Pakistan's military, which has launched an intelligence-based offensive against them.
The BLA blew up a railway track and took over 400 train passengers hostage in an attack in March that killed 31.
