STORY: A building at the Zaporizhzhia nuclear plant was set ablaze during intense fighting, Ukrainian authorities said on Friday, triggering fears of a potential nuclear disaster. The blaze was later extinguished.

"Russian people, I want to appeal to you: how is this possible? After all we fought together in 1986 against the Chernobyl catastrophe," Zelenskiy said in a televised address, evoking memories of the world's worst nuclear disaster.

"You have to ... take to the streets and say that you want to live, you want to live on earth without radioactive contamination. Radiation does not know where Russia is" the president added.