Three Chinese language teachers and their Pakistani driver were killed in a suspected suicide bombing in the southern city of Karachi, police say. The blast ripped through their minibus, injuring at least four others near the university's Confucius Institute. The separatist Baloch Liberation Army (BLA) said it attacked the vehicle carrying the Chinese staff, and that the suicide bomber had been a woman. The group opposes Chinese investment in Pakistan, saying locals do not benefit. It would be the first time a suicide attack by the BLA has been carried out by a female militant. The group has targeted Chinese nationals on a number of occasions, as has the Pakistani Taliban. China has condemned the attack that killed three of its citizens in Pakistan and demanded Islamabad fight against those involved. The incident poses a key challenge for a government freshly-installed after weeks of political turmoil. A long-time ally and key investor in the country, China is heavily involved in large development projects across Pakistan. But the BLA, which is banned in Pakistan, opposes Chinese investment in the country, saying locals do not benefit. "China expresses its strong condemnation and great indignation at this major terrorist attack," deputy director of the Chinese foreign ministry Zhao Lijian tweeted on Wednesday. He urged Pakistani authorities to "deal with the aftermath" and "resolutely fight against terrorist organizations involved in the case". Top level Pakistan officials have also scrambled to appease China since the incident. New Prime Minister Shahbaz Sharif made a personal visit to the Chinese embassy in Islamabad on Tuesday to meet officials. In a rare move, He also presented them with a handwritten letter, reaffirming his government's commitment "to eliminating all militants and terrorists from Pakistani soil". "We won't rest until the culprits are hunted down and given exemplary punishment," he wrote. The chief minister of Sindh province - of which Karachi is the capital - also visited the Chinese consulate, reassuring officials that Pakistan "values the services rendered by Chinese experts in the country and the province" and that those involved would be "brought to justice". In a statement, Pakistan's foreign office spokesperson Asim Iftikhar termed the incident "reprehensible" and a "direct attack" on Pakistan-China relations. Former prime minister Imran Khan, who was ousted from power in early April, also weighed in, calling the incident "yet another attack with a specific agenda of trying to undermine Pakistan-China strategic relationship". China's embassy in Pakistan confirmed that three of the country's citizens had been killed in Tuesday's blast. Pakistan's government condemned what it called a "cowardly terrorist attack". The dead included the director of the Confucius Institute, a Chinese government-run body which offers language and cultural programs overseas, and two other faculty members in Karachi. CCTV footage showed a woman standing outside the gate of the institute as the van arrives, followed by a powerful explosion. The BLA released a photo of a woman in fatigues raising two fingers in salute who it said had carried out the attack, and named her as Shariah Baloch alias Bramsh. Local media reported that the bomber had been a student at the university. Balochistan, rich in natural resources but Pakistan's poorest province, is home to a long-running insurgency. It is being transformed by major Chinese infrastructure projects on the China-Pakistan Economic Corridor (CPEC), a network of roads, railway and pipelines between the two countries which forms part of Beijing's ambitious Belt and Road initiative. The three Chinese nationals killed were teaching at the Confucius Institute of University of Karachi, which aimed to "deepen international understanding of Chinese language and culture, and promoting people-to-people exchanges between China and Pakistan". Since its inception in 2013 however, the faculty members - who were mostly Chinese nationals - had faced threats to their safety and had to follow strict security protocols, according to Pakistan daily newspaper Dawn. They were escorted by a security detail to and from the institute every day and to their classrooms, where students would be frisked before being allowed to enter. The Confucius Institute is a Chinese government-run global education program. The institutes are seen as a way to exercise "soft power", with China spending approximately $10 bn (£7.8 bn) a year on CIs and related programs, according to a 2018 report from the Council of Foreign Relations. The institutes operate in cooperation with affiliate colleges and universities around the world. However, the close relationship between these institutes and the Chinese government has sparked concerns over issues like academic freedom and political influence, especially over controversial topics like Taiwan, Tibet and Uighurs in Xinjiang. In 2020, the US designated the Confucius Institute as a foreign propaganda mission, saying it was "owned or effectively controlled" by a foreign government. — BBC