Novoyavorivsk, Ukraine—Just after 3 in the morning on Sunday, air-raid sirens rang out over this bucolic town in the far west of Ukraine. Residents hustled downstairs into bomb shelters, listening for the telltale sounds of munitions. This was the third night of sirens in the Lvivska Region—the Ukrainian air defenses sound the alarm if there is even the possibility of a strike happening nearby—after a period of five days without alarms. People in Novoyavorivsk felt secure.

Then, shortly after 5:30 in the morning, residents started to hear explosions. Eight missiles slammed into a military base where, until early March, British troops had been involved in joint training programs with Ukrainian forces. In recent weeks, foreign fighters joining Ukraine’s foreign legion were based there. More than 20,000 foreigners, including a number from the United States, have joined the Ukrainian Foreign Legion. Up to 1,000 foreign fighters were staying at the base, according to The New York Times. Preliminary reports put the number of dead at anywhere between nine and 39. Some 57 were said to be wounded. It was unclear Sunday morning if foreign fighters had been killed in the strike.

Halfway into the third week of Russia’s war on Ukraine, the attack on the base near Novoyavorivsk—just 12 miles from the Polish border—is the closest strike on NATO territory since the beginning of the conflict. It occurred near the city of Lviv, which is a transit point for hundreds of thousands of refugees fleeing the Russian advance, and a base for foreign journalists and diplomats. In Poland, anti-Russian sentiment is running high, and any perceived attack on Polish forces or territory risks drawing NATO into a wider war with Russia.

The strike came a day after Moscow’s foreign minister, Sergei Ryabkov, warned the United States on Russia’s Channel One not to transfer weapons to Ukraine, and said that convoys with weapons for Ukraine could be targeted. He did not specify whether such strikes would take place only on Ukrainian soil. According to the Ukrainian government, some 38 missiles were fired at Novoyavorivsk from across the Belarussian border, and eight breached Ukraine’s air defenses. Two days ago, Russian missiles struck targets outside the nearby cities of Lutsk and Ivanofrankivsk. Though Belarus has not officially declared its role in the war, the European Union has said it considers Minsk to be a party to the conflict and has sanctioned Belarussian figures.

The giant base that was struck is known as the International Peacekeeping and Security Center. At 390 square kilometers (approximately 150 square miles), it is one of the the largest such facilities in the region; the base can host almost 1,800 soldiers, but the Ukrainian government hasn’t disclosed how many troops were there at the time of the explosions.

Olha Mandarenko, a 64-year-old resident of Kyiv, fled to this town from her home when the war began in late February and Russian troops began shelling the capital. A former shopkeeper with piercing blue eyes, Olha thought she would be safe in Novoyavorivsk. She brought her six grandchildren with her. “But now we don’t feel safe,” she said.

“Bombing, we heard bombing from the northern direction. As a woman, I don’t really know what is going on there. Our windows started to shake, and we heard sirens,” she said. “We stayed in bed. Our kids kept sleeping. Only the adults woke up.”

At around 9 on Sunday morning, under slate gray skies, a group of around 40 emergency workers in red overalls stood grimly around an Okko gas station on the outskirts of town here. We observed some 50 ambulances screaming up and down the road from Lviv. At a checkpoint near the base, tense soldiers waved the press away. “We have no information right now,” a medic said. “We are waiting for directions. All the ambulances have been called here, and we have been asked to wait.”

Yarema Kachmar, the head of the Lviv Regional Department of Emergency Medical Care and Disaster Medicine, was at the scene coordinating ambulance drivers. He said two separate areas had been struck. “A lot of people have been wounded,” he said.

Behind the counter at the local pharmacy, Oleh Fetik, 21, told us that he heard several explosions on Sunday morning. “We didn’t hear any planes. We just heard bombs,” he said. “My parents woke up, we left the house and we saw the yellow sky. We hid ourselves in a shelter and we were there until 6 am.” Another man behind the counter chimed in, “We heard five explosions and then, after a pause of 15 minutes, two more.” Double-tap airstrikes, which overwhelmingly target first responders heading to collect the wounded after a bombing or a missile strike, are widely viewed as war crimes. “We’ve heard the sound of training at the base for the last couple of years, but these strikes were much more powerful, and the sound was very strong,” the man, who did not identify himself, said. “Our windows were shaking.”

Olha, the former shopkeeper, said her experience of life had informed her view of the current war. “Because I worked in a shop all my life, I understand that people need to eat. People in Moscow just understand they need to bomb,” she said. “They bombed everyone. If they worked in my profession, they would understand that people need different things in this life. They don’t understand that people need to eat, people need bread, they don’t need bombs.”

Many people here have called for NATO countries to “close the skies” over Ukraine—to enforce a no-fly zone. But President Biden has repeatedly ruled out calls for US jets to enforce a no-fly zone over fears that such a move could push Moscow closer to a nuclear conflict. “That’s called World War III,” Biden warned last week.

For her part, Olha blamed European countries for not doing more. “Europe has to be punished for taking such slow decisions. Right now, they are having their comfortable lives and eating good food while kids are dying here,” she said. But she reserved her choicest words for President Vladimir Putin of Russia. “This person comes from the past century. He’s from the KGB,” she continued. “The whole world has to stand up. This person, Putin, cannot even be called a person, attacking such a peaceful country. We just built up everything. Our kids started to have more possibilities in life, our lives improved, we stood up. The new generation should understand this. They are traveling the world, they are seeing Europe, so why is their government doing this? Why do Russians send their kids here to be buried in a forest? Later their mothers won’t be able to find them.”

She shook her head as she thought of her grandchildren. “Why are they putting up the Iron Curtain again?” she asked. “Russian people want to travel the world. They don’t just want to go to Magadan, to the Gulag. This is ruining the lives of so many young people.”

Additional reporting and translation by Anna Ivanova.