China has labelled a blast outside Karachi Airport in Pakistan on Sunday a “terrorist attack”.

Two workers from China were killed in the explosion which injured at least eight, officials from both countries said.

Police and the provincial government said a tanker exploded just outside of the country’s biggest airport.

A Chinese Embassy statement said a convoy carrying Chinese staff of the Port Qasim Electric Power Company had been attacked around 11pm, killing two Chinese and injuring one other.

It said there were Pakistani casualties as well.

Provincial home minister Zia Ul Hassan told local TV station Geo the explosion was an attack targeting foreigners.

Thousands of Chinese workers are in Pakistan, most of them involved in Beijing’s multibillion-dollar Belt and Road Initiative that connects south and central Asia with the Chinese capital.

Videos showed flames engulfing cars and a thick column of smoke rising from the scene. There was a heavy military deployment at the site, which was cordoned off.

The Chinese statement said China is working with Pakistan to handle the aftermath.

It called for a thorough investigation to punish the perpetrators and reminded Chinese citizens in the country to take safety precautions.

“The Chinese Embassy and Consulates General in Pakistan strongly condemn this terrorist attack (and) express deep condolences to the innocent victims of both countries,” the statement said.

Deputy Inspector General East Azfar Mahesar told the media that it seemed like it was an oil tanker explosion.

“We are determining the nature and reasons for the blast. It takes time,” he said.

Police officers were among the injured, he added.

The home minister and inspector general also visited the blast site, but they did not talk to the media.

Rahat Hussain, who works in the civil aviation department, said the blast was so big that it shook buildings throughout the air facility.