Gunmen killed 20 miners and wounded another seven in Pakistan's southwest, a police official said Friday. It's the latest attack in the restive Balochistan province and comes days ahead of a major security summit being hosted in the capital.

Police official Hamayun Khan Nasir said the gunmen stormed the accommodations at the coal mine in Duki district late Thursday night, rounded up the men and opened fire. Most of the men were from Pashtun-speaking areas of Balochistan.

Three of the dead and four of the wounded were Afghan. Nobody claimed immediate responsibility for the attack. The province is home to separatist groups who want independence. They accuse the federal government in Islamabad of unfairly exploiting oil- and mineral-rich Balochistan at the expense of locals.

On Monday, a group called the Baloch Liberation Army said it carried out an attack on Chinese nationals outside Pakistan's biggest airport. There are thousands of Chinese working in the country, most of them involved in Beijing's multibillion-dollar Belt and Road Initiative.

The explosion, which the BLA said was the work of a suicide bomber, also raised questions about the ability of Pakistani forces to protect high-profile events or foreigners in the country. Islamabad is hosting a summit next week of the Shanghai Cooperation Organization, a grouping founded by China and Russia to counter Western alliances.