At least six people were killed and around 90 wounded on Friday when Russian drones attacked a shopping center in the central Ukrainian city of Kryvyi Rih, local authorities said.

Six children were among the wounded in the daytime attack on President Volodymyr Zelenskiy’s hometown, regional governor Oleksandr Hanzha said on the Telegram messaging app.

“Twenty-one people are in serious condition, including one child,” he said.

He posted a photo of black smoke billowing from a large industrial building.

Zelenskiy called the attack “absolutely cynical and despicable”, saying that a second Russian drone hit the shopping center half-an-hour after the first in a deliberate attempt to target emergency services.

“Attacks like these are nothing less than terrorist acts,” Zelenskiy said on Telegram, urging the world to hold Russia to account.

Russia is escalating its air war on Ukraine as fighting on the battlefield grinds toward the 4-1/2 year mark. On Thursday, 17 people were killed in a Russian ballistic missile attack on the Ukrainian capital Kyiv.

Ukraine has also stepped up its own attacks on Russia, targeting oil facilities and logistics infrastructure to try to undermine Moscow’s ability to wage war.

(Reporting by Dan Peleschuk and Daniel Flynn; Editing by Alison Williams and Toby Chopra)