While both sides ruled out a Christmas truce in the nearly 10-month-old war, Ukrainian forces staged their heaviest shelling attack in years in the country’s Russian-controlled east on Thursday.

Alexei Kulemzin, the Russian-backed mayor of Donetsk city, said 40 rockets were fired from BM-21 Grad multiple rocket launchers at civilians in the city center in the early hours.

Meanwhile, Russian forces kept up shelling and airstrikes along the entire eastern front line, killing one person, while two were killed in the southern city of Kherson, Ukrainian officials said.

“The Kremlin … is seeking to turn the conflict into a prolonged armed confrontation,” a senior Ukrainian officer, Brig. Gen. Oleksiy Gromov, told a briefing, also dismissing the possibility of a truce over the festive period.

Kulemzin cast the Donetsk attack as a war crime and said it was the biggest on the city since 2014, when pro-Moscow separatists seized it from Kyiv’s control. Preliminary estimates showed five people had been hurt, including a child, he said.

Ukraine’s military General Staff said Moscow’s focus remained on the eastern cities of Bakhmut and Avdiivka, and that Ukrainian forces had repelled Russian attacks.