A spokesman for Europe’s largest nuclear plant says the facility is on fire after Russia attacked the power station in the southern Ukrainian city of Enerhodar.

A government official said that elevated levels of radiation are being detected near the site of the Zaporizhzhia nuclear plant, which provides about 25% of the country’s power generation.

The official spoke on condition of anonymity because the information has not yet been publicly released.

Plant spokesman Andriy Tuz told Ukrainian television that it is urgent to stop the fighting to put out the flames.

Enerhodar is a city on the Dnieper River that accounts for one-quarter of the country’s power generation.

Russian forces battled for control of the Ukrainian city that is home to the biggest nuclear power plant in Europe on Thursday and gained ground in their bid to cut off the country from the sea, as Ukrainian leaders called on citizens to rise up and wage guerrilla war against the invaders.

The fighting at Enerhodar, a city on the Dnieper River that accounts for one-quarter of the country’s power generation, came as another round of talks between the two sides yielded a tentative agreement to set up safe corridors inside Ukraine to evacuate citizens and deliver humanitarian aid.

While the huge Russian armored column threatening Kyiv appeared bogged down outside the capital, Vladimir Putin’s forces have brought their superior firepower to bear over the past few days, launching hundreds of missiles and artillery attacks on cities and other sites around the country and making significant gains in the south.