Three loud explosions were heard earlier in the city center and dense black smoke could be seen rising from afar. Air raid sirens sounded before the explosions. Maksym Kozytsky, the head of Lviv’s regional military administration, later reported on his Telegram account three more explosions after hitting the fuel depot, saying: “The air alarm remains.” Lviv is a strategic Ukrainian city near the Polish border that has largely escaped the relentless bombing of much of the country during the Russian invasion. It was a stunning attack, taking place just one day after the Russian military said the first phase of the conflict was over and that it was turning its attention to the disputed eastern parts of Ukraine. The attack took place as US President Joe Biden was in Poland on Saturday, where he met with his Polish counterpart Andrei Duda, as well as with Ukrainian officials and refugees. Biden later delivered a speech outside the Royal Castle in the Polish capital, Warsaw, in which he strongly stated that Russian President Vladimir Putin “can not stay in power.” The White House said in a statement that Biden was not seeking a change of government. Earlier in the day, Biden told the Ukrainian people: “We stand with you. Biden was informed of the strike in Lviv before leaving his hotel for his speech, according to a White House official. “Now in the eternal struggle for democracy and freedom, Ukraine and its people are at the forefront, fighting to save their nation and their courageous resistance is part of a broader struggle for … basic democratic principles that unite everyone. free people. said Biden. Sadovyi said on Twitter on Saturday that Russian troops had attacked the city, but did not elaborate. He called on the residents to stay in shelters. An industrial facility in Lviv used to store fuel burned as a result of one of the Russian strikes, according to Sadovyi. “As a result of the bombing, one of the industrial facilities is burning. It is fuel storage,” said the mayor. He did not specify whether this was the cause of the smoke. The mayor added that “no residential infrastructure was damaged”. Sadovyi later confirmed that another blow had struck Lviv, causing “significant damage” to the city’s infrastructure. Residential buildings were not damaged, he added. Meanwhile, Ukrainian authorities said on Saturday that convoys of buses trying to evacuate civilians had been stopped and detained by Russian forces as part of what they claimed was a pressure campaign to force some residents to go to Russia. In a statement, Oleksandr Starukh, head of the Zaporizhzhia regional administration, said an evacuation convoy of more than 50 buses leading from the besieged Ukrainian port of Mariupol to Zaporizhzhia was held overnight at a Russian checkpoint in Vasilia, about 35 miles south. of Zaporizhia. Starukh said the escort included two ambulances carrying three children in need of emergency medical care. Saturday’s strikes were not the first in Lviv. Several Russian missiles hit an aircraft repair plant there on March 18. Work on the facility had stopped before the strikes and there were no reports of casualties. Saturday’s attacks come after a top Russian general claimed on Friday that the “first phase” of Russia’s military plan had been completed, with a focus on eastern Ukraine. It was not clear whether the statement implied a shift in targets for the Russian military or merely a change in public messages. “In general, the main tasks of the first stage of the operation have been completed,” Colonel Sergei Rudskoi, Russia’s first deputy chief of staff, said in a statement. “The combat potential of the Ukrainian armed forces has been significantly reduced, allowing us, I reiterate, to focus our main efforts on achieving the main goal – the liberation of Donbass.” After days of Western leaders demonstrating their united front against Russia, Saturday’s strikes could be seen as a response by Putin and his military to Biden and the West. The Russian military has said it does not target civilians or residential areas, despite overwhelming evidence to the contrary. CNN’s Chandler Thornton, Kaitlan Collins, Kevin Liptak and Maegan Vazquez contributed to this report.