LVIV, Ukraine >> Russia fired cruise missiles Thursday at a western Ukraine city far from the front line of the war, killing at least six people in an apartment building in what officials said was the heaviest attack on civilian areas of Lviv since the Kremlin’s forces invaded the country last year.

Emergency crews with search dogs went through the rubble of the building after the nighttime attack destroyed the roof and the top two floors. At least 36 people were injured, according to authorities.

The youngest of the people who died was 21 years old and the oldest was a woman of 95, Lviv province governor Maksym Kozytskyi said. “This woman survived the Second World War, but unfortunately she didn’t survive” Russia’s full-scale invasion of Ukraine, Kozytskyi said.

Debris and wrecked parked cars lined the street outside the building, which overlooks a small neighborhood park with swings and other playground equipment.

Lviv Mayor Andriy Sadovyi said the body of a woman was pulled from the rubble late Thursday, bring the death toll to six. Kozytskyi said seven survivors were rescued from wreckage and a total of 14 people hospitalized. Sadovyi said around 60 apartments and 50 cars in the area of strike were damaged. He announced two days of official mourning.

U.S. Ambassador to Ukraine Bridget Brink described the attack as “vicious.”

“Russia’s repeated attacks on civilians are absolutely horrifying,” she tweeted.

Ukraine’s air force reported it intercepted seven of the 10 Kalibr cruise missiles that Russia fired from the Black Sea toward the Lviv region and its namesake city — more than 800 kilometers (500 miles) away — around 1 a.m. Thursday.

The Kremlin’s forces have repeatedly hit civilian areas during the war, though Russian officials say they choose only targets of military value.

Lviv is near the western border with Poland and is more than 500 kilometers (300 miles) from Kyiv and 700 kilometers (425 miles) from the frontline southern Ukraine region of Kherson; Kyiv’s counteroffensive to dislodge Russian forces in southern and eastern Ukraine is in its early stages.

Sadovyi, the mayor, addressed residents in a video message, saying the attack was the largest on Lviv’s civilian infrastructure since the beginning of last year’s invasion.

Lviv resident Ganna Fedorenko suffered injuries to her face, where an adhesive plaster on her cheek had turned red with blood. She held her hands crossed on her chest as she reacted to the attack.

“Russians are hitting us. That’s how they love us. I’m sorry for those people who were killed. They were young. So sorry for them,” she said. “This is terrible. They hit civilians.”

The Ministry of Internal Affairs said 64 people had to leave their homes.

Ukrainian President Volodymyr Zelenskyy promised “a response to the enemy. A tangible one.”

He went later Thursday on an official trip to Bulgaria at the invitation of its new pro-Western government, with talks about weapon supplies and Ukraine’s NATO membership on the agenda.

Ukrainian air force updates about the missiles’ course during the night showed they flew to the Kyiv region first, then turned west toward Lviv. Russia often changes the route of their missiles and drones to find weak spots in Ukraine’s air defenses.

In the early days of the war, Lviv served as a main transit point for millions of refugees from different parts of the country that crossed the border to Europe. Hundreds of thousands of Ukrainians from the east and south remained in the calmer and safer Lviv.

Like the rest of the country, Lviv suffered power outages when Russia fired hundreds missiles over the winter, aiming to destroy Ukraine’s energy system. However, the attacks in the city were not as frequent as in the capital Kyiv, and Thursday’s strike was a deep shock for many in the city.

Ukrainians shared messages of support on social media for Lviv residents.