QUETTA, Pakistan (AFP) — Twenty coal miners were shot dead in an overnight attack by a group of heavily armed men who laid siege to their lodgings in Pakistan’s southwestern Balochistan province, police said Friday.

Separatist militant groups in Balochistan regularly target natural resource extraction projects dotted across the mineral-rich province, the poorest in Pakistan.

Up to 40 attackers fired at miners for half an hour starting around 12:30 a.m. “before escaping into the night,” said Asim Shafi, police chief in Duki district, where the attack took place.

“They had rocket launchers and hand grenades with them,” he told Agence France-Presse.

A senior government official in the district, Kaleemullah Kakar, also confirmed the death toll and said seven more people had been wounded.

“The attackers also set fire to the machinery on-site,” he said.

There were conflicting reports about where the victims hailed from.

Many extraction schemes in Balochistan are financed and operated by foreign countries — most notably neighboring China — which the armed factions accuse of hoarding wealth.

Militant group the Baloch Liberation Army (BLA) claimed a Sunday night bombing on a vehicle convoy in southern Karachi that killed two Chinese coal plant workers.

But ethnic Baloch militants also regularly target migrant laborers from elsewhere in Pakistan, particularly Punjabis hailing from the east.

Punjabis are Pakistan’s largest ethnic group and dominate the nation’s military forces, which have been battling the insurgency in Balochistan for decades.

In August, the BLA carried out coordinated attacks across Balochistan that killed dozens of mostly Punjabis.

Friday’s attack comes just days before Pakistan is due to host a summit of government heads from the Shanghai Cooperation Organization, a regional bloc established by China and Russia.