LJUBLJANA, Slovenia (AP) — An explosion at a chemical plant in southeast Slovenia injured at least 10 people on Thursday as authorities urged residents in the vicinity to stay indoors.

The explosion was reported around 8.30 a.m. (0630GMT) in Kocevje. It wasn’t immediately clear what caused the blast.

The town, which is about 55 kilometers (30 miles) southeast of the capital Ljubljana, has a population of about 8,000.

“We advise all residents in the surrounding area to close their windows and not to go out in the open during the intervention," regional N1 television quoted local police as saying. “They also should not go near the scene.”

The report said that a local emergency council met for an urgent session as firefighters and emergency crews rushed to the Melamin factory.

Melamin produces chemical products such as melamine resins for paper, construction, wood, rubber, and the lacquer industry, impregnated decorative paper for the furniture industry, and impregnated materials for footwear manufacturing.

The factory has about 200 employees.