KYIV, Ukraine — At least 11 people were reported killed in attacks in Ukraine’s war-ravaged northeast on Sunday as Russia pushed ahead with its renewed offensive.

In the Kharkiv region, the focus of the offensive, the Kharkiv Regional Prosecutor’s Office said six people were killed and 27 wounded in a Russian strike on the outskirts of the regional capital, also called Kharkiv.

Regional Gov. Oleh Syniehubov said that five more people were killed and nine wounded in an attack on the region’s Kupiansk district, southeast of the regional capital.

Russia’s Ministry of Defense said Sunday that its forces in the area were “continuing to advance into the depths of the enemy’s defense.”

Ukraine’s General Staff said Russia had stepped up its attacks around Kharkiv and that the situation was “dynamic.”

Russia launched an offensive in the Kharkiv region late last week, significantly adding to the pressure on Ukraine’s outnumbered and outgunned forces which are waiting for delayed deliveries of crucial weapons and ammunition from Western partners.

Ukraine’s overstretched forces are trying to slow Russia on the new front by using bomb-laden drones to destroy military vehicles.

Russian President Vladimir Putin said on Friday during a visit to China that Moscow’s offensive in the Kharkiv region aims to create a buffer zone but that there are no plans to capture the city.

Meanwhile, Ukraine and Russia continued to exchange drone attacks.

Ukrainian air force officials said Sunday morning that air defenses shot down all 37 Russian drones launched against the country overnight.

In Russia, Russian air defenses shot down 57 Ukrainian drones over the southern Krasnodar region overnight, the Russian Defense Ministry said.

Local military officials said drone debris hit an oil refinery in the town of Slavyansk-on-Kuban, but there was no fire or damage.

News outlet Astra published videos appearing to show an explosion at the refinery as it was hit by a drone. The videos could not be independently verified.

Nine long-range ballistic missiles and a drone were destroyed over the Russia-occupied Crimean Peninsula, following Friday morning’s massive Ukrainian drone attack that cut off power in the city of Sevastopol.

A further three drones were shot down over the Belgorod region, which borders Ukraine. According to regional Gov. Vyacheslav Gladkov, a church roof was set on fire by falling drone debris, but there were no casualties.

The Russian-installed governor of Ukraine’s partially occupied Kherson region, Vladimir Saldo, said that one person died and 16 were wounded when a Ukrainian drone hit a minibus on Sunday morning.