A suicide bomber rammed a vehicle into a convoy of Chinese engineers working on a dam project in northwest Pakistan on Tuesday, killing six people, police said, the third major attack on Chinese interests in the South Asian country in a week, Reuters reported.

The first two attacks hit an airbase and a strategic port in the southwest province of Balochistan where China is investing billions in infrastructure projects.

The engineers were on their way from Islamabad to their camp at the dam construction site in Dasu in the Khyber Pakhtunkhwa province, Mohammad Ali Gandapur, the regional police chief, told Reuters.

“Five Chinese nationals and their Pakistani driver were killed in the attack,” Gandapur said.

Dasu is the site of a major dam and the area has been attacked in the past. A blast on a bus killed 13 people, including nine Chinese nationals, in 2021.

Chinese engineers have been working on a number of projects Pakistan with Beijing investing over $65 billion in infrastructure projects as part of the China Pakistan Economic Corridor (CPEC) under its wider Belt and Road initiative.

No one claimed responsibility for Tuesday’s attack, nor was there a claim for the 2021 attack. Pakistan is home to twin insurgencies – one by Islamists and the other ethnic militants seeking secession, read the report.

While Chinese interests are primarily targeted by the ethnic militants seeking to push Beijing out of mineral-rich Balochistan, they generally operate in the country’s south and southwest – far from the site of Tuesday’s attack.

Islamists mostly operate in the country’s northwest in the area the convoy was attacked.

The Khyber Pakhtunkhwa police had reached the spot and started relief operations, Reuters reported.

A separate police source told Reuters the convoy was carrying staff of the construction firm China Gezhouba Group Company (CGGC) working on the Dasu hydropower project – the same company targeted in 2021.

Construction work ceased for months after that attack.

China’s embassy in Islamabad did not immediately respond to an emailed request for comment.

The attacks come a week before Prime Minister Shehbaz Sharif is expected to fly to Beijing, according to a source in the Prime Minister’s Office. It will be Sharif’s first visit since taking office following February elections.

Pakistani Foreign Minister Ishaq Dar condemned the attack, and said the country would continue to fight back against militants.