QUETTA — Unknown gunmen shot dead seven passengers on a Lahore-bound bus in southwestern Pakistan's Balochistan province after forcing them off the vehicle and checking their identity documents late on Tuesday (Feb 18), officials said.

Balochistan, bordering Afghanistan and Iran, is a key battleground in Pakistan's fight against separatist insurgents, who want greater autonomy and a share of the region's natural resources.

In recent months, there has been a surge in attacks on security forces, Chinese infrastructure projects and workers from richer central Punjab province, who the militants see as exploiting Baloch resources.

The group of around 40 men stopped multiple buses and vehicles along a highway in Balochistan's Barkhan district, checking national identity cards before pulling seven passengers off the bus and shooting them, senior government official Waqar Khurshid Alam told Reuters.

All seven victims were from Punjab, Alam said.

"Armed men dragged my elder brother from the bus after checking his identity card, but they did nothing with us," a woman from the city of Faisalabad in Punjab said in a video seen by Reuters.

No group has claimed responsibility for the attack, and the motive behind the killings was unclear. Officials told Reuters that the area had been cordoned off but the attackers had escaped.

Pakistan's Prime Minister Shehbaz Sharif said the gunmen would be brought to justice.

"Those who harm the lives and property of innocent citizens will have to pay a heavy price," Sharif said in a statement.

The killings are a bloody reminder of a roadside attack in August when armed men shot dead 23 people after checking passenger IDs and later setting the vehicles on fire.

That attack was part of a wave of violence by separatist militants in Balochistan targeting police stations, infrastructure, and civilians. At least 73 people were killed.

The Baloch Liberation Army (BLA), the biggest of several ethnic armed groups batting the central government, took responsibility for that operation, which it called "Haruf" or "dark windy storm".

On Friday, a bomb targeting a vehicle carrying coal miners killed at least 11 people and wounded six others. No group has claimed responsibility.

The Baloch Liberation Front, another separatist outfit, said on Friday it had carried out eight separate attacks on security forces in the past week, but not the one on the coal miners.

Insurgent groups have also targeted Chinese nationals and interests in Balochistan.

China is developing the deep-water Gwadar seaport, which is also in the province.

Beijing has invested heavily in regional development projects as part of a US$65 billion (S$87 billion) commitment under the China-Pakistan Economic Corridor part of the Belt and Road Initiative.

Source: Reuters