Three Chinese language teachers and their Pakistani driver were killed in a suspected suicide bombing in the southern city of Karachi, police say.
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 is heavily involved in large infrastructure projects across Pakistan, including in resource-rich Balochistan province.
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 programmes 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.