Ukrainian units that have crossed the Dnieper River to the left (or eastern) bank of the river in Kherson are facing heavy attacks from Russian forces, an official said Wednesday.

The Kherson region, in southern Ukraine, is partly under Russian occupation after a failed attempt by Ukraine to capture the city of Kherson last year forced Russia to retreat to the eastern bank of the river.

Ukraine announced Tuesday that it had secured a bridgehead on the eastern bank of the river. The move could signal the beginning of a push toward Crimea, which is occupied by Russia. Ukraine said on Wednesday that it was starting to resist Russian forces on the eastern bank.

A Russian-appointed official, Vladimir Saldo, confirmed for the first time in a Google-translated message on Telegram that Ukrainian units had crossed the river. He said that Ukraine had initially sent “more troops than our weapons could destroy.”

He said that “more forces have now arrived” and claimed that Ukrainian forces were trapped in the village of Krynki where “a fiery hell” was waiting for them. “Bombs, missiles, ammunition from heavy flamethrower systems, artillery shells, and drones are flying at them [Ukrainian forces] … In the last two or three days alone, the enemy lost about a hundred fighters.”