Eight years after a pro-European protest movement toppled a Kremlin-backed president in Kyiv and Russia fomented a grinding war in the country’s east, people in Ukraine have been on tenterhooks wondering what Russian President Vladimir Putin might do next. Their worst nightmare began to unfold as dawn broke on Thursday, after Putin declared the start of a “special military operation” in Ukraine. As he spoke, people in Kyiv, Kharkiv, Odessa and other parts of the country woke to the sound of large explosions and air raid sirens. In disbelief, they turned on their TVs and radios to hear news that an invasion had begun, with Russian troops breaching borders to the north and south. A large boom at 6 a.m. shook Yana and Sergii Lysenko from sleep in their Kyiv home. At first, Yana thought her husband was mistaken, it couldn’t be an attack, and told him to go back to sleep. Then they heard another blast. “We started to listen to the news and we understood that the war had started, the Russian invasion is ongoing,” Sergii told CNN. After hearing from friends that traffic had clogged roads out of the capital, the couple decided at first to remain at home with their 3-year-old daughter, packing their bags just in case. “We are a bit in shock and trying to stay calm, not to show anything to our child,” Sergii added. By the afternoon, Yana and Sergii had decided to leave their Kyiv home. They jumped into the car and started heading west to Ternopil, a town 300 miles west of Kyiv, about 120 miles from the Polish border. “We think it will be more safe in Ternopil. The last thing was when we heard the bomb, that’s why we decided to get out from the city because we are living in the center,” Yana told CNN from the car, as they were driving away. Despite Western warnings that an attack was imminent, Ukrainians have largely remained divided about the possibility of a Russian invasion, hoping that the military buildup was just the latest in Moscow’s mind games. After months of ratcheting tensions, the wide-scale military assault still came as a shock – especially in Kyiv, where residents had, until Wednesday, continued to go about their daily lives as foreign governments withdrew their diplomatic staff from the capital. The mood was entirely different on Thursday morning, as people queued to purchase fuel for cars and drive west, away from the focus of the Russian assault. Exit ramps out of Kyiv were snarled with traffic for hours after explosions rang out near the city’s main airport. Grocery stores, pharmacies and shops were crammed with people trying to stock up on supplies. In one 24/7 supermarket, 20-year-old Oleksandr, who declined to give their surname, told CNN shelves had been emptied of pasta and bread. Long lines formed with people trying to withdraw cash from ATMs, many of which had run empty – a scene that was playing out in other parts of the country. In the center of Mariupol, in the country’s southeast, one woman told CNN she had been driving around the city all morning, trying 10 different ATMs while her children waited in the idling car for her outside. People in the port city on the Sea of Azov were frantic and confused, as rumors ran rampant that roads and checkpoints were closed, preventing them from leaving. Across the country, Ukraine’s subway stations are doubling as bomb shelters, as the assault continues and fears of strikes grow. In Kharkiv, Ukraine’s second-largest city, people were pouring underground while distant booms sounded intermittently. Families with their children and pets in tow descended on one subway station after reports that Russian forces had rolled across the border and were heading toward the city in Ukraine’s northeast. People gathered there said they have vehicles but don’t want to risk leaving the city. One woman there captured the uncertainty and insecurity being felt by people across the country, who are now wondering how their lives could have changed so dramatically from day to night. “You wake up at 5 a.m. to a totally new reality, and you find out the world is no longer the safe place you imagined,” she told CNN. “It’s hard to believe it’s actually our neighbor doing this, because we never really believed that our neighbor can just come and just grab our land and tell us what to do. We (are an) independent country of Ukraine, and … we don’t want to be a part of Russia or any other country,” she said, breaking down in tears. “I can’t believe it’s happening, really.” Back in Kyiv, the capital’s subway system was up and running. Some residents were camped out, sheltering in stations, but most were trying to find some way out of the city, with small suitcases and bags in tow. A student rushing out of the station at Kyiv’s Independence Square, the epicenter of the 2014 Maidan revolution and living monument to the so-called “Heavenly Hundred” protesters who died there, said that her parents, who live some 190 miles west, were coming to pick her up after she had failed to find any other transport options. “I woke up at 5 a.m. and packed. I’ve been to the railway station and it’s closed. There are no buses,” Diana, 20, told CNN, adding: “I’m going home because I’m scared.” But some people say they are carrying on as though it’s “business as usual.” Alex Klymenok, a 27-year-old lawyer, woke up to the sound of explosions and then resolutely put on his suit, traveling into his office to pick up a laptop and return home to work remotely. “Well, it’s scary, of course, but we don’t need to panic. All they want us to do at this moment is to panic,” Klymenok told CNN, adding that he still did not believe Putin would launch a full-scale invasion, moving forces beyond the separatist-held regions of Donetsk and Luhansk, which Moscow recognized as independent on Monday. “For now, it’s business as usual. But if they’re here in Kyiv, I’m ready to, I am prepared to fight,” he said. Any sense of an impending showdown had hardly been felt in Lviv, a historic cultural hub in the country’s west, until Thursday morning, when air raid sirens sounded for the first time, outside of regular drills, since World War II. Like clockwork, the picturesque city transformed from a tourist hotspot to a place preparing for war. Even as TV screens flashed warnings of an imminent attack on the country in recent days, tour groups continued to flock the city’s cobblestoned streets, where dazzling baroque-style architecture stretches for miles. Diplomatic missions and international groups had also fled to the relative safety of Lviv from the capital Kyiv. But that bubble burst on Thursday. Most shops in the city were shuttered. Long lines extended outside the few open stores – pharmacies, supermarkets and even pet stores. The wait was more than two hours long at most petrol pumps, where fuel was being rationed in an attempt to prevent shortages. Svetlana Locotova let out a hearty laugh from a long line outside a cash machine. She was on the phone with her relatives in the heavily shelled city of Kharkiv. Next to her was Margarita, her 12-year-old daughter. Speaking to CNN, but also – it would seem – to her daughter, who nervously forced a smile, Locotova said cheerily: “It’s totally normal that this would happen. I expected this queue. This is just how people react.” She and Margarita had just returned from a shooting range – a common pastime here lately. “We’re confident, but we’re preparing for the worst,” she said. People here were going about the day with an air of defiance, even as the city seemed transformed. “Ukraine is no stranger to war” is the common refrain. Many people still exchanged smiles and jokes, even as they spoke about preparing their homes to receive relatives from the significantly harder-hit east of the country. As the threat of invasion has loomed larger, residents across the country have prepared for the worst – packing emergency evacuation kits and spending their weekends training as reservists. As that threat was realized, Ukraine’s defense minister urged anyone thinking of taking up arms to enlist. In Kharkiv, 25 miles from the Russian border, hundreds of reservists joined up with Ukraine’s Territorial Defense Forces to learn battle skills and survival techniques. The volunteers, who only weeks earlier learned how to use a rifle and bandage a wounded comrade with a tourniquet, are now facing the prospect of being deployed to the front lines. There were reports on Thursday morning of long lines outside one of Kharkiv’s hospitals, where people were desperate to help by donating blood. And in a quiet moment in one of the city’s main squares, as many on the border wondered what might come next, a small group huddled together in the freezing cold and knelt down on the pavement to pray.