“Enemy air strikes were recorded in 10 spots,” the Ukrainian Air Force said.
The mayor of the western city of Rivne, Oleksandr Tretyak, called it “the largest attack” on the region since the start of the war.
Regional governor Oleksandr Koval said 70 buildings – including private houses and a nursery – were damaged in the attack.
Russia said it had targeted an airfield near the village of Dubno in the Rivne region.
“This is one of the retaliatory strikes against terrorist attacks by the Kyiv regime on Russian military airfields,” its defence ministry said.
Russia had vowed revenge last week and had already called strikes on Kyiv retaliation to the brazen Ukrainian operation.
Ukraine also said it had launched its own overnight strike on an electronics factory that makes parts for Russian drones, in the city of Cheboksary in Chuvashia, which lies 600km east of Moscow.
Russian officials said the facility had to temporarily suspend production after the attack.
“This morning, Ukrainian attempts to use drones in Chuvashia were detected,” Chuvashia Governor Oleg Nikolayev said on Telegram, adding: “Two drones fell on the territory of the VNIIR factory.”
Ukraine’s army said the factory manufactured “antennas for Shahed” (drones). Russia fires dozens of Iranian-designed Shahed attack drones at Ukrainian cities on a daily basis.
Russia said a Ukrainian strike killed one person in its border Kursk region Monday.
The acting governor of the region, Alexander Khinstein, said the strike hit a “cultural-service centre” in the Rylsky district, killing a 64-year-old man.
-Agence France-Presse