A massive blast outside Karachi Airport in Pakistan on Sunday killed two people and injured at least eight, officials said.

Police and the provincial government said a tanker exploded outside the airport, which is Pakistan’s biggest.

But the provincial home minister, Zia Ul Hassan, told local TV station Geo that it was an attack targeting foreigners.

A Home Ministry official told The Associated Press that it was an attack on Chinese nationals, one of whom was injured. He spoke on condition of anonymity because he was not authorized to talk to the media.

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.

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

“We are determining the nature and reasons for the blast. It takes time.” 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 press.

Rahat Hussain, who works in the civil aviation department, said the blast was so big that it shook the airport’s buildings.