Russian force surrounded the Ukrainian capital city Sunday evening, cutting off the country’s largest city.

The mayor of Kyiv, Vitali Klitschko, told The Associated Press Sunday that civilians could no longer be evacuated from the city, as it has been encircled by Russian soldiers.

“We can’t do that, because all ways are blocked,” he said. “Right now we are encircled.”

Klitschko said that since the Russian invasion last Thursday, nine civilians have been killed in the city of 2.8 million, including one child.

Earlier on Sunday, Ukrainian officials said Russian forces had entered Kharkiv, the second-largest city in Ukraine.

Ukrainian forces battled Russian troops in urban combat on the streets of Kharkiv, with videos posted to social media showing Russian combat vehicles moving through the city.

But Iryna Venediktova, Ukraine’s top prosecutor, claimed that the Russian army has thus far been unable to secure control of the city of 1.5 million.

During the battle in Kharkiv Sunday, Russian forces blew up a gas pipeline, Ukraine claimed, with the Ukrainian government claiming the explosion would cause an “environmental catastrophe”.