At least 13 workers are dead, and another 38 were injured after a furnace exploded Sunday at a nickel factory owned by a Chinese company, according to officials.

The explosion occurred on the island of Sulawesi, at a factory in the Morowali Industrial Park.

Chinese nickel and steel giant Tsinshan operated the factory. The company has stakes in the nickel mining industry in Indonesia, operating under the company’s local arm, Indonesia Tsingshan Stainless Steel (ITSS).

Ipda Hamid, spokesperson for the Morowali police, said to the CNN affiliate CNN Indonesia, that there were 13 deaths at the scene, and multiple victims had been taken to local hospitals to be treated for injuries. Hamid said the local police had taken over the scene and were conducting an official investigation.

Reuters reported that among the dead were eight Indonesians and five Chinese workers.

A statement issued by the company said the blast occurred in the course of repairs of a furnace. The statement said, “During the repairs process, an explosion occurred. Based on initial investigations, it (was) possibly caused because there was still some explosion-inducing liquid at the bottom of the furnace.”

Hamid said that there were several oxygen canisters nearby which exploded and fueld the fires.

As the world’s biggest exporter of nickel, Indonesia also has generous quantities of copper, cobalt, and bauxite, which is used to make batteries for electric vehicles. For that reason, Indonesia has emerged as a leading global supplier, and has been seeking foreign investment in smelters and processing plants from foreign investors in countries such as China, where electric vehicles are a rapidly growing industry.

However critics have noted that in the rush to develop its nickel processing capacity, the nation has failed to account for the damage done to the environment, as well as farmers and indigenous tribes which are harmed by the industry.

In a statement, Indonesian politician and labor activist Said Iqbal demanded the Indonesian Manpower Ministry open an investigation, saying, “The (operator) must bear the costs of medical treatment and accident compensation for those affected.”

He added, “There must also be heavy sanctions for those who violate regulations.”