Indonesia declared a state of emergency in a port city on Borneo island on Tuesday after an oil spill spread along the coast, Reuters reported. The oil spill started on Saturday and resulted in a fire that killed four fishermen over the weekend.

The spill has now spread over an area of 18 sq km in the Balikpapan city. It is contaminating the sea and polluting the air with thick black smoke, The Guardian reported. The city has distributed masks to people to help them cope with the smell.

Disaster mitigation officials were able to control the fire, but are still trying to contain the spill. The city’s environment authorities warned the public not to carry out activities that could spark fires.

Balikpapan, with a population of 7 lakh, is a major mining and energy centre and has an oil refinery. Pertamina, the state-owned company that runs the refinery, said it was investigating where the oil spill originated.

“We are in a state of emergency because of the oil spill’s impact,” said Balikpapan city Secretary MN Fadli. “I may sound like I’m exaggerating, but the state of the bay is like that of a gas station.”

Around 1,200 people in the Penajam North Penajam Paser sub-district reported symptoms of nausea, vomiting and breathing problems.