The governor of Luhansk in eastern Ukraine says Russian forces now control about 80 percent of the city of Severodonetsk, which is said to be the last Ukrainian stronghold in the region.
In a social media post on Wednesday, Luhansk Governor Serhiy Haidai also said street battles are continuing in the city.
He noted that Ukrainian troops have managed to push back Russian forces in some districts, and they captured six Russian soldiers.
Russian troops are intensifying their offensive in and around the city in a bid to put all of the Luhansk region under their control.
Russia's defense ministry said on Wednesday it shot down a Ukrainian fighter jet and attacked troops with missiles in Donetsk, a region neighboring Luhansk.
Meanwhile, the US Department of Defense has said it is sending four High Mobility Artillery Rocket Systems, or HIMARS, to Ukraine as part of additional military assistance. The department says HIMARS provides increased precision and extended range.
Speaking to reporters on Wednesday, a senior Defense Department official said the systems have already been positioned inside Europe to ensure the most rapid delivery to Ukraine.
German Chancellor Olaf Scholz has also pledged additional military support for Ukraine. Addressing the German parliament on Wednesday, Scholz said his government will provide Ukraine with the most modern air defense system the country possesses.