KRAMATORSK, Ukraine (AP) — A day after Russian President Vladimir Putin declared victory in seizing an eastern Ukraine province essential to his wartime aims, his troops escalated their offensive in the neighbouring province Tuesday, prompting the governor to urge a mass evacuation of residents.

Governor Pavlo Kyrylenko said that getting the 350,000 people remaining in Donetsk province out is necessary to save lives and to enable the Ukrainian army to better defend towns from the Russian advance.

“The destiny of the whole country will be decided by the Donetsk region,” Kyrylenko told reporters in Kramatrosk, the province’s administrative center and home to the Ukrainian military’s regional headquarters.

“Once there are less people, we will be able to concentrate more on our enemy and perform our main tasks,” Kyrylenko said.

The governor’s call for residents to leave appeared to represent one of the biggest suggested evacuations of the war. According to the UN refugee agency, more than 7.1 million Ukrainians are estimated to be displaced within Ukraine, and more than 4.8 million refugees left the country since Russia’s invasion started on February 24

The governor said that because they house critical infrastructure such as water filtration plants, Russia’s main targets are now Kramatorsk and a city 16 kilometers 10 miles) to the north, Sloviansk. Kyrylenko described the shelling as “very chaotic” without “a specific target … only to destroy civilian infrastructure and residential areas.”

Sloviansk also came under sustained bombardment Tuesday. Mayor Vadim Lyakh said on Facebook that “massive shelling” pummeled Sloviansk, which had a population of about 107,000 before Russian invaded Ukraine more than four months ago. The mayor, who urged residents hours earlier to evacuate, advised them to take cover in shelters.

At least one person was killed and another seven wounded Tuesday, Lyakh said. He said the city’s central market and several districts came under attack, adding that authorities were assessing the extent of the damage.

The barrage targeting Sloviansk indicated that Russian forces were positioned to advance farther into Ukraine’s Donbas region, a mostly Russian-speaking industrial area where the country’s most experienced soldiers are concentrated.