A large fire has erupted overnight at the plant for alkaline paints and resins "Orgahim" in Bulgaria's Danube city of Ruse.

The Ruse Mayor, Plamen Stoilov, reported early Thursday morning that the fire has been tamed. Three workers have inhaled harmful gases – they were sent to the local hospital and later released.

The crisis headquarters of the City Hall further inform that there is no danger for residents and visitors of the city. The Regional Governor of Ruse, Stefko Burdzhiev, told the TV channel bTV that precisely because of the fact that there was no immediate threat for the population, the blaze had not been officially reported via the alarm system.

In addition to thick smoke and the blaze, several secondary explosions have occurred along with a partial gassing of Ruse.

Inspectors from the Regional Inspectorate of the Environment and Waters are measuring harmful substances on the hour. The results are yet to be announced.

According to initial information, the fire erupted over overheating of the boiler system of the plant. Seven people have been inside the four-story building. The amount of chemicals stored there remains unknown.

Around 1 am, the Chief of the Regional Police Directorate has requested additional fire brigades from the cities of Silistra and Veliko Tarnovo because there were two remaining small outbreaks, but the blaze has been localized.

The call about the fire has been placed at 9 pm. Police and fire rescue teams have been immediately sent to the location along with ambulances.

The authorities are probing the cause of the fire.