An explosion ripped through a van within a university campus in southern Pakistan’s Karachi on Tuesday, killing three Chinese nationals and their Pakistani driver, according to officials. A separatist militant group claimed credit for the incident, which they said was carried out by a female suicide bomber.

University spokesman Mohammad Farooq said that the attack at the University of Karachi also injured a fourth Chinese national as well as a Pakistani guard escorting the van.

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According to Karachi police commissioner Ghulam Nabi Memon, the early investigation indicates that the incident was carried out by a suicide bomber. He claimed that closed-circuit television footage from the scene showed a woman clad head-to-toe in the female burqa walking up to the van, followed by an instantaneous explosion.

Among those killed in China were the director of the Chinese-built Confucius Institute, which offers Chinese language graduate studies, and two teachers.

In the past, the Baluchistan Liberation Army, a militant group in neighbouring Baluchistan province, has targeted Chinese nationals in attacks.

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Following the incident on Tuesday, the group issued a statement identifying the bomber as Shari Baluch or Bramsh, claiming she was the organisation’s first female bomber. According to the statement, the attack marked “a new chapter in the history of Baluch resistance.”

Baluchistan has long been the site of a low-level insurgency led by armed Baluch organisations seeking more autonomy and a larger part of the region’s natural resources, if not outright independence from Islamabad.

However, the Pakistani Taliban has previously targeted Chinese interests. Last July, the group, also known as the Tehreek-e-Taliban Pakistan, claimed responsibility for an attack on a bus in Pakistan’s northern Khyber Pukhtunkhwa region that killed nine Chinese people. Four Pakistanis were also killed in the attack.

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The Pakistani Taliban are distinct from the Afghan Taliban, who have seized control in neighbouring Afghanistan.

Thousands of Chinese employees live and work in Pakistan, and the majority of them are participating in Beijing’s multibillion-dollar “One Belt, One Road Project,” which aims to connect south and central Asia with the Chinese capital.

The China-Pakistan Economic Corridor includes a significant road connecting Pakistan’s southern port of Gwadar in southwestern Baluchistan region with China’s northwest Xinjiang province. The project involves various infrastructure projects as well as several power projects.