Gunmen killed at least 20 people at a coal mine in Pakistan's southwestern province of Balochistan, according to local police.
The attackers stormed the homes of Junaid Coal Company mine workers in the province's Duki district early Friday morning, gathered the men together and opened fire.
A hospital in Duki received 20 bodies and is treating six injured, Reuters reported.
The workers were attacked with heavy weapons, including rockets and grenades, according to police.
The attackers also set fire to the mine's machinery.
Police confirmed that four of the victims were Afghans, while the other men were from Pashtun-speaking areas of Balochistan.
Businesses closed their doors on Friday in anticipation of an expected protest in Duki's main square.
So far, no group has claimed immediate responsibility for the killings, but in the past the separatist Baloch Liberation Army (BLA) has carried out several deadly attacks in the province.
On Monday, a BLA militant killed two Chinese nationals and injured at least 10 people in a suicide attack near Karachi airport.
The group, which campaigns for an independent Balochistan, also carried out multiple attacks in August that killed more than 50 people. Pakistani authorities responded by killing 21 insurgents in the province.
The latest attack on the miners was condemned by Balochistan Chief Minister Sarfraz Bugti, who said the attackers aimed to destabilize Pakistan.
“Terrorists have once again targeted the working poor…the killing of these innocent workers will be avenged,” he said in a statement.
Balochistan is home to several separatist groups who accuse the central government of exploiting the resource-rich province.
Militants often target security forces, as well as people who come to work on the province's many mining and infrastructure projects.
The recent violence comes ahead of the Shanghai Cooperation Organization, a major security summit to be held next week in the Pakistani capital Islamabad.
In addition to strengthening security measures, Pakistani authorities are reportedly restricting the movements of Chinese citizens during the summit, due to the security risk posed by militant groups targeting them.
