Russian forces overnight attacked Ukraine with drones and missiles, killing at least six people and wounding 11 more in Kharkiv, Ukraine’s second largest city, local officials reported.

Governor of the Kharkiv region Oleh Syniehubov said missile strikes on the city damaged residential buildings, a gas station, a kindergarten, a cafe, a shop and cars.  Kharkiv is only about 18 miles from the eastern border with Russia.

Overall, Russia fired 32 Iranian-made Shahed drones and six missiles at Ukraine overnight, according to the air force commander. Ukrainian air defense forces shot down three cruise missiles and 28 drones, Lt. Gen. Mykola Oleshchuk said in a statement. “Russian killers continue to terrorize Ukrainians and attack Kharkiv and other peaceful cities,” he said.

The Russian military has not commented on the strikes, but said that Ukraine on Saturday morning fired Vampire rockets at Russia. All 10 of them were shot down over Russia’s border region of Belgorod by air defense systems, the Russian Defense Ministry said.

On the ground in Ukraine, Russian forces were advancing, and pushing back against them was “difficult,” said Oleksandr Syrskyi, commander of Ukraine’s armed forces.

Syrksyi said the situation in the Bakhmut area in the partially occupied eastern Donetsk region was particularly challenging. He said Russian forces are carrying out offensive operations day and night, using assault groups with the support of armored vehicles, as well as assaults on foot.

Fierce battles are taking place east of the town of Chasiv Yar, which Ukraine still controls and which is located near the occupied city of Bakhmut.

Russian forces are trying to break through defensive lines there, Syrskyi said on the messaging app Telegram, adding that “Chasiv Yar remains under our control, all enemy attempts to break through to the settlement have failed.”

Near Avdiivka, another city in the Donetsk region held by the Russians, the fiercest battles were occurring in Pervomaiskyi and Vodyanyi, according to the official. He also said the situation is tense on the southern and northeastern parts of the front line.

In January, more than 40 Russian missiles slammed into Ukraine’s two largest cities, killing at least seven and leaving 60 more wounded, according to Ukrainian officials, as Moscow again dismissed any diplomatic resolution to the two-year war backed by Kyiv and its Western supporters. The Russian missiles targeted Ukraine’s capital Kyiv and Kharkiv, damaging about 30 residential buildings in the latter and shattering around 1,000 apartment windows, leaving residents exposed to frigid winter weather, regional  Syniehubov said.

Mayor Ihor Terekhov of Kharkiv was quoted by the French news agency AFP as saying an entire section of a multi-floor apartment building was toppled and an unknown number of people left trapped under the rubble.