Ukraine said a Russian missile attack killed seven people in Lviv on Monday, the first civilian victims in the western city, and reported signs that Russia had started its anticipated new offensive in the east.

Maksym Kozytskyy, the governor of Lviv, which lies 60 kilometers (40 miles) from the Polish border, said preliminary reports suggested there were four strikes, three on warehouses that were not in use by the military and another on a car service station.

"It was a barbaric strike at a service station, it's a completely civilian facility," he told a news conference.

Andriy Sadoviy, mayor of Lviv, said the youngest victim among the dead was aged 30. The blast also wounded 11 and shattered windows of a hotel housing Ukrainians evacuated from elsewhere in the country, he added.

"Seven peaceful people had plans for life, but today their life stopped," the mayor said.

Driven back by Ukrainian resistance in the north, Moscow has refocused its ground offensive in the two eastern provinces known as the Donbass, while launching long-distance strikes at other targets, including the capital, Kyiv.

Ukraine's armed forces command said it believed that Russia had started a new push for control of the east, increasing the intensity of attacks.

"This morning, along almost the entire front line of Donetsk, Luhansk and Kharkiv regions, the occupiers attempted to break through our defenses," Security Council Secretary Oleksiy Danilov said in televised comments.

"They began their attempt to start the active phase this morning," he said.

The regional governor of Kharkiv said that authorities were continuing the evacuation of people from two areas where they expect fighting to take place.

A man and a woman were killed in Kharkiv on Monday when shells hit a playground near a residential building, the prosecutor's office said in a post on Telegram messaging service.

Howitzer training

Russia denies targeting civilians in what it calls a special operation to demilitarize Ukraine and eradicate what it calls dangerous nationalists. It rejects what Ukraine says is evidence of atrocities, saying Ukraine has staged them to undermine peace talks.

Western capitals and Kyiv accuse Russian President Vladimir Putin of unprovoked aggression.

The United States military expects to start training Ukrainians on using howitzer artillery in coming days, a senior U.S. defense official said on Monday.

Last week, U.S. President Joe Biden announced an additional $800 million in military assistance to Ukraine, expanding the aid to include heavy artillery ahead of a wider Russian assault expected in eastern Ukraine.

The official, speaking on condition of anonymity, said the howitzer training would take place outside Ukraine.

French President Emmanuel Macron on Monday said that his dialogue with Putin had stalled after mass killings were discovered in Ukraine.

Russia's defense ministry said it had hit hundreds of military targets in Ukraine overnight. It said air-launched missiles had destroyed 16 military facilities in the Kharkiv, Zaporizhzhia, Donetsk and Dnipropetrovsk regions and in the port of Mykolayiv, which are in south and east Ukraine.

It added that the Russian air force had launched strikes against 108 areas where Ukrainian forces were concentrated and Russian artillery struck 315 Ukrainian military targets.

'Hell on earth'

Russia is trying to take full control of the southeastern port city of Mariupol, which has been besieged for weeks and which would be a huge strategic prize, linking territory held by pro-Russian separatists in the east with the Crimea region that Moscow annexed in 2014.

Major Serhiy Volyna, commander of Ukraine's 36th marine brigade, which is still fighting in Mariupol, appealed for help in a letter to Pope Francis, saying women and children were trapped among fighters in the city's steelworks.

"This is what hell looks like on earth ... It’s time (for) help not just by prayers. Save our lives from satanic hands," the letter said, according to excerpts tweeted by Ukraine's ambassador to the Vatican.

No fewer than 1,000 civilians were hiding in underground shelters beneath the vast Azovstal steel plant, the city council said on Monday.

Video and audio footage showed explosions rumbling and smoke rising from the steelworks, which contain myriad buildings, blast furnaces and rail tracks.

Russia's invasion has damaged or destroyed up to 30% of Ukraine's infrastructure at a cost of $100 billion, a Ukrainian minister said, adding reconstruction could be achieved in two years using frozen Russian assets to help finance it.

The Office of the U.N. High Commissioner said on Monday that the civilian death toll from the war in Ukraine had surpassed 2,000, reaching 2,072 as of midnight on April 17 from the start of the Russian invasion on Feb. 24.

About 4 million Ukrainians have fled the country.