Insurgents assaulted two military facilities in Pakistan’s Balochistan province overnight, killing four troops and injuring 15 of their own men, a top official said on Thursday, in the latest bloodshed in the resource-rich region where China is investing.

The assaults occurred only hours before Prime Minister Imran Khan left for the start of the Winter Olympics in Beijing, where he would meet with President Xi Jinping and other world leaders.

“Our armed forces repulsed the big attacks,” Minister of Interior Sheikh Rasheed Ahmad said in a video statement.

Four soldiers and 15 insurgents were killed while four or five insurgents were surrounded and the army would deal with them, he said.

The Baloch Liberation Army (BLF) group claimed responsibility in a statement sent to a Reuters reporter, saying its suicide bombers had detonated explosive-laden vehicles at the entrance of the bases killing more than 50 soldiers.

Last week, the insurgents killed 10 soldiers in an attack on a post near the port of Gwadar on the Arabian Sea, the heaviest casualty toll for the army in the Balochistan insurgency in years.

Ethnic Baloch guerrillas have been fighting the government

for decades for a separate state, saying the central government unfairly exploits Balochistan’s rich gas and mineral resources.

They usually attack gas projects, infrastructure and the security forces. They also attack Chinese projects, and occasionally kill Chinese workers despite Pakistani assurances that it is doing everything it can to protect the projects.

China is involved in the development of the Gwadar port and other projects in the province as part of a $60 billion China-Pakistan Economic Corridor, which is part of Beijing’s Belt and Road initiative.

China has been raising its security concerns with Pakistan, especially after 10 Chinese workers were killed and 26 were wounded in an attack in northern Pakistan last year.

Pakistan has approved $11.6 million in compensation for the victims’ families.

Khan and his team would be exploring economic opportunities on the visit to Beijing, including trying to persuade Chinese businesses to set up in Pakistan, Finance Minister Shaukat Tarin said.