The attack by the Baloch Liberation Army outside the airport in the southern port city of Karachi on Sunday was the latest deadly assault on Chinese in the country and came a week before Pakistan is to host a summit of the Shanghai Cooperation Organisation, a security grouping founded by China and Russia to counter Western alliances.
Initially, Pakistani authorities gave conflicting details and indicated the explosion might have been from an oil tanker but police later confirmed it was a bomb attack.
Pakistani news channels broadcast videos of flames engulfing cars and a thick column of smoke rising from the scene. Troops and police cordoned off the area.
On Monday, counterterrorism officials were investigating how the attacker reached Karachi, Pakistan's largest city.
Among the wounded were also police officers who were escorting the Chinese convoy when the attack happened.
The spokesman for the separatist group, Junaid Baloch, said om Monday that one of their suicide bombers targeted the convoy of Chinese engineers and investors as they left the airport.
The Baloch Liberation Army is mainly based in the restive southwestern Balochistan province but it has also attacked foreigners and security forces in other parts of Pakistan in recent years.
The Chinese embassy in Islamabad said Chinese staffers working at the Port Qasim Electric Power Company - a coal-powered power plant that's a joint China-Pakistan venture - were in the convoy when it came under attack.
Two Chinese nationals were killed and one was wounded, the embassy said, adding there were also Pakistani casualties but did not elaborate.
Pakistan's foreign ministry denounced the bombing, saying it was a "heinous terrorist attack near Karachi airport".
It said another Chinese was injured in the attack.
Prime Minister Shehbaz Sharif said the attackers were "enemies of Pakistan" and promised the perpetrators would be punished.
Pakistan hosts thousands of Chinese workers as part of Beijing's multibillion-dollar Belt and Road Initiative, which is building major infrastructure projects.
The outlawed separatist group, which seeks independence for Balochistan, has repeatedly warned against any Chinese working in Balochistan.
The Sunday attack followed deadly attacks in August that killed more than 50 people in Balochistan.
Sharif at the time said the attackers sought to harm Chinese-funded development projects.
