QUETTA, Pakistan (Reuters) -Unidentified gunmen attacked a cluster of small private coal mines in southwestern Pakistan early on Friday, shooting some miners as they slept and lining up others before opening fire, killing 21 in the restive region, police said.
The attack by 40 armed men days before Pakistan hosts a summit of the Shanghai Co-operation Organization grouping is the worst in weeks in the mineral-rich province of Balochistan bordering Afghanistan and Iran.
"The armed terrorists remained for around 1-1/2 hours in the mining area," regional police official Asif Shafi told Reuters. "They fired rockets and hurled grenades at the mines and miners' quarters."
There was no immediate claim of responsibility for the attack on the mines of the Junaid Coal Co in the Duki area, which injured six. Among the dead were four Afghan nationals and another four were injured.
Businesses and shops were shut in Duki as hundreds of people gathered along with the bodies of the dead in a protest to demand the arrest of the attackers, police said.
"We were receiving threats from the militants for some time but there was no information about the attack," said mine-owner Khairullah Nasar, who is also the chairman of the district council.
The attackers burnt down all 10 mines, along with the equipment and machinery within, he added.
A decades-long insurgency in Balochistan has led to frequent militant attacks against the government to press demands for a share of regional resources.
Several attacks have targeted migrant workers, including some from Afghanistan, employed by smaller, privately operated mines.
The government was "determined to root out all forms of terrorism", Prime Minister Shehbaz Sharif said in a statement.
"The provincial government has ordered an investigation and a case has been registered against unknown assailants under the terrorism law," a government official said, speaking on condition of anonymity.
Pakistan has seen a resurgence in Islamist militancy since 2022, when a ceasefire between the Pakistani Taliban and the government broke down.
Two Chinese nationals working for a power plant were killed this week in a blast in the southern city of Karachi, for which the Baloch Liberation Army (BLA), one of several insurgent groups battling the government, claimed responsibility.
The BLA was also behind Balochistan's most widespread violence in years in August, which targeted police stations, railway lines, and highways, killing more than 70 people.
Armed men who stormed the residence of labourers from the eastern province of Punjab last month killed seven.
On Friday, cross-fire between police and attackers killed two suspected militants involved in a 2021 attack on dam project workers that killed 13, including nine Chinese nationals.
(Reporting by Saleem Ahmad, Ariba Shahid, and Mushtaq Ali; Writing by Gibran Peshimam and Sakshi Dayal; Editing by YP Rajesh and Clarence Fernandez)
