Politics A Timeline of How Russia Began Invading Ukraine The situation in Ukraine continues to evolve, with the country declaring a state of emergency as Russia attacked earlier this week By Virginia Chamlee Virginia Chamlee Twitter Virginia Chamlee is a Politics Writer at PEOPLE. She has been working at PEOPLE for three years. Her work has previously appeared in The Washington Post, Buzzfeed, Eater, and other outlets. People Editorial Guidelines Published on February 25, 2022 05:39PM EST Share Tweet Pin Email Mariupol, Ukraine, on Thursday. Photo: Evgeniy Maloletka/AP/Shutterstock Months of tensions climaxed this week with Russia beginning a long-feared invasion of Ukraine — a still-unfolding situation that officials say has already claimed more than 100 lives. The incursion followed a build-up on Russian troops on the Ukraine border stretching back to last year and warnings from the U.S. that Russia would face harsh sanctions if it did indeed illegally enter its neighbor. Amid the fog of war, here's a look at what's been confirmed, moment-by-moment, about how the initial stages of the invasion unfolded, as detailed by the Associated Press, CNN and other outlets. Moscow evacuates its Ukrainian embassy After months of speculation about an impending attack, Moscow evacuated its embassy in Kyiv, the Ukraine capital, on Wednesday, a move that raised concerns that military action was imminent. That same day, Ukraine's parliament overwhelmingly approved a state of emergency and urged citizens in Russia to get out of the country. Troops begin crossing over from Russia The first signs of the Russian invasion took place in the pre-dawn hours on Thursday local time, when camera footage at a border crossing station between Crimea and Ukraine revealed people wearing camouflage fatigues entering the area — after which the cameras were seemingly and abruptly turned off. Russian President Vladimir Putin. RUSSIAN PRESIDENT PRESS SERVICE/HANDOUT/EPA-EFE/Shutterstock Putin announces "special military operation" Less than an hour after the footage was recorded, Russian President Vladimir Putin delivered a speech littered with falsehoods, invoking claims of "genocide" in Kyiv as a pretext for his invasion. His "special military operation," he claimed, was meant to "protect people who have been subjected to abuse and genocide by the Kyiv regime for eight years" (a claim that he often repeats without evidence). Putin denied that Russia planned "to impose anything on anyone by forces," but offered a strongly-worded message to any Ukrainians attempting to defend their homeland. "We urge you to lay down arms immediately and go home. I will explain: all servicemen of the Ukrainian army who comply with this requirement, can freely leave the area of military actions and return to their families." Russia Is in 'Beginning of an Invasion' of Ukraine, U.S. Says Emilio Morenatti/AP/Shutterstock Strikes begin Minutes after Putin's Thursday morning speech, reports of missile attacks and explosions were reported across Ukraine. Russian forces assaulted the country from three sides, with those in the cities of Odessa, Dnipro, Mariupol and Kramatorsk all reporting large blasts (many of which were at military bases, though civilian areas were also attacked). A wide array of weaponry — including helicopters, tanks, and long range artillery — have been used in the attack, according to reports based on footage collected during the events. Explosions, airstrikes or troop movements have touched multiple cities, including the capital of Kyiv, a city of 2.8 million, the AP reported. Pierre Crom/Getty Citizens flee as air travel becomes impossible As explosions began, Ukraine's Ministry of Infrastructure announced an evacuation of passenger and staff from the Kyiv airport and the Ukraine airspace was closed to commercial flights. Thousands of Ukrainians have fled or attempted to flee via borders to the west, leading experts to warn of an oncoming refugee crisis. In an address to the United Nations Security Council emergency meeting on Monday, U.S. ambassador to the U.N. Linda Thomas-Greenfield said that the conflict already had dire consequences: Roughly 3 million Ukrainians were in need of "food, shelter and lifesaving assistance." The U.N.'s high commissioner for refugees, Filippo Grandi, wrote on Twitter on Friday, "More than 50,000 Ukrainian refugees have fled their country in less than 48 hours — a majority to Poland and Moldova — and many more are moving towards its borders." What's at Stake in Russia-Ukraine Crisis: War, Economic Hardship and World Order 'Pulled at the Seams' Sergei Grits/AP/Shutterstock Ukraine declares martial law As the first Russian strikes unfolded on Thursday, Ukrainian President Volodymyr Zelenskyy addressed the nation, saying "Dear Ukrainian citizens, this morning President Putin announced a special military operation in Donbas. Russia conducted strikes on our military infrastructure and our border guards. There were blasts heard in many cities of Ukraine." Zelenskyy continued: "We're introducing martial law on the whole territory of our country," inferring that Ukrainian soldiers — and not police officers — would be creating and enforcing laws. Ukraine also severed all diplomatic relations with Russia, with Zelenskyy saying that some civilians would soon be taking up arms and that weapons would be given to anyone who wants one. The Ukrainian leader again addressed the nation Thursday evening, saying, "Now the fate of the country depends entirely on our army, on our heroes, our security forces, all our defenders. And on our people, your wisdom and the great support of all friends of our country. Glory to Ukraine!" The Russian attack on Ukraine is an evolving story, with information changing quickly. Follow PEOPLE's complete coverage of the war here, including stories from citizens on the ground and ways to help.