(CNN) — The city of Mykolaiv, in southern Ukraine, came under heavy bombardment in the early hours of Sunday morning, according to officials, as Russian President Vladimir Putin used his country’s Navy Day to broadcast more militaristic threats to anyone who undermines Russia’s “sovereignty and freedom.”
Mykolaiv Mayor Oleksandr Senkevych said the cluster munitions smashed windows and destroyed balconies. “Mykolaiv was under massive shelling today. Probably the heaviest since this started,” he said in a statement.
A CNN crew on the ground heard explosions caused by the attacks and saw fires that broke out in the shelling. Residents interviewed by CNN also said it was the heaviest shelling in the city since the start of the war.
At least one person was killed and two wounded in the attack, according to Vitalii Kim, head of the Mykolaiv regional military administration.
In a speech marking Russia’s Army Day in St. Petersburg, Putin did not mention Russia’s war in Ukraine, but said the “current situation in your country calls for very decisive action.”
“We will provide protection firmly and by all means. The key here is the ability of the Navy, which is capable of responding with lightning speed to anyone who decides to usurp our sovereignty and freedom,” Putin said.
Putin said delivery of the country’s Zircon hypersonic cruise missile systems would begin in the coming months. Russia said in May that it had successfully tested the Zircon missile over a range of 1,000 kilometers.
War crimes accusations
Separately, at least three people were killed and eight wounded in the fighting in eastern Ukraine, according to the Donetsk civil-military administration, which said villages in the region were hit by artillery, Russian Grad missiles and Uragan rockets.
“11 private residential buildings and one high-rise building, a police station, a market, a canteen were damaged, and three fields were burned,” the administration said.
Ukraine’s General Staff said Russian forces were attacking front lines in the Donetsk and Luhansk regions.
Ukrainian President Volodymyr Zelensky on Saturday called on the remaining residents of the Donetsk region to evacuate urgently in what he called a “government decision”.
“Everything is being organized. Full support, full assistance, both logistics and payments,” he said in his late-night speech. “We just need a decision from the people themselves, who haven’t made it for themselves yet.”
An attack on a prison in separatist-controlled eastern Ukraine on Friday resulted in the deaths of at least 40 prisoners. Olenivka prison near Donetsk has been used to house many of the Ukrainian soldiers who surrendered at the Azovstal plant in Mariupol several months ago.
UK Ambassador to Ukraine Melinda Simmons said the strike was part of a pattern of “the worst kind of human rights abuses” on her Twitter on Saturday. “Olenivka needs to be investigated. She appears to be part of an increasingly worrying pattern of the worst kind of human rights abuses and potential war crimes being committed with impunity in occupied eastern Ukraine,” the ambassador tweeted.
Zelensky called the attack “a deliberate war crime on the part of the Russians.”
Ukrainian intelligence said the attacks were carried out by the Russian Wagner mercenary group and were not coordinated with the Russian Defense Ministry. CNN cannot independently verify the allegations made by Ukrainian military intelligence.
Russia has blamed Ukraine for the attack.