At least six people were killed on Thursday when a convoy of oil workers was ambushed by gunmen in Pakistan's restive Balochistan province, officials said.
The province, bordering Afghanistan and Iran, is the poorest in the country despite being rich with oil and gas, and remains home to Islamist, separatist and sectarian insurgents.
Paramilitary troops and workers from the state Oil and Gas Development Company (OGDCL) were among those killed in the attack on a highway in Gwadar, a senior official told AFP.
"The death toll may rise," he said, requesting anonymity as he was not authorised to talk to media.
A second official confirmed the incident and details.
No group has claimed responsibility for the attack.
Balochistan is key to the China-Pakistan Economic Corridor, part of Beijing's regional Belt and Road infrastructure initiative.
The corridor seeks to connect China's western province of Xinjiang with Gwadar, giving Beijing access to the Arabian Sea.
The province's roughly seven million inhabitants have long complained they do not receive a fair share of its gas and mineral wealth.
In a separate attack in North Waziristan, six soldiers were killed by a roadside bomb, the military said in a statement.
The northwestern region along the Afghan border was once a focal point in the global war on terror but attacks by militant groups have decreased following a series of army offensives.
Piyush Goyal and Jonathan Reynolds tour the Royal Opera House in London
