At least four people, including three Chinese nationals, were killed as an explosion ripped through a van inside a university campus in southern Pakistani port of Karachi on Tuesday, police said.
The explosion targeted the vehicle near the University of Karachi's Confucius Institute, a Chinese language learning center.
Television images showed plumes of smoke billowing high from the van as security forces cordoned off the area.
Muqadas Haider, a police official, told reporters that among the dead were three Chinese teachers, including two women.
According to Raja Umer Khitab, head of Karachi police's counter-terrorism cell, the attack was carried out by a female suicide bomber.
CCTV footage from the site showed a person dressed in a burka walking up to the van, followed by an explosion.
The Balochistan Liberation Army (BLA), an outlawed Baloch insurgent group, claimed responsibility for the attack.
The group in southwestern Balochistan province, which attacks infrastructure and security forces, has targeted Chinese nationals in the past. In a statement, the BLA said its "first-ever" woman suicide bomber carried out the attack.
China and Pakistan are "all-weather" strategic partners, with the two nations cooperating in various sectors.
Many Chinese workers are living and working in Pakistan, with most of them involved in the multi-billion dollar China Pakistan Economic Corridor, a flagship project of Beijing's Belt and Road Initiative.
Signed in 2014, the $64 billion project aims to connect China's Xinjiang province to Gwadar port in Balochistan. It includes a number of infrastructure and power projects.
Newly elected Prime Minister Shehbaz Sharif expressed grief and sorrow over the loss of Chinese nationals. "I strongly condemn this cowardly act of terrorism. The perpetrators will surely be brought to justice," he said in a tweet.
Last July, nine Chinese workers were killed in a suicide attack in northern Pakistan.