ZAGREB, Croatia (AP) — Firefighters in eastern Croatia were battling to contain a huge fire in a plastics factory on Wednesday, and authorities asked residents to remain indoors and keep their widows shut.

The fire erupted early Wednesday in the Drava International factory complex in the town of Osijek, spreading quickly and sending thick dark smoke high in the air.

Emergency services said that large amounts of plastics stored in an open area were on fire, making it difficult for firefighters to control the raging blaze.

“The temperature is unbelievable, horrible,” said Boris Banjan, deputy commander of the regional firefighting unit. “Our equipment is melting.”

The state HRT television reported that two firefighters were slightly injured. The report said firefighters managed to take out large amounts of flammable liquid from the fire zone, preventing further incidents.

The fire also forced the closure of a road, police said. Some schools canceled classes for the day.

The TV said a strong wind fueled the spread of the polluted smoke. Burning of plastics releases toxic gases but the level of pollution was not immediately clear.

The civil protection authorities in the area urged citizens to “close down their windows and not go out unless absolutely necessary.”

The Drava International factory produces plastic packaging and other products. Croatian media reported that there have been four incidents in the factory in the past 12 years, killing one person.