Officials say a Russian drone barrage has targeted the center of Kharkiv, injuring nine people and damaging a maternity hospital in Ukraine’s second-largest city.

Russia launched its largest drone and missile bombardment of Ukraine overnight into Wednesday, according to Ukrainian President Volodymyr Zelenskyy.

Russia and Ukraine struck each other with hundreds of drones on Sunday, throwing Russian air travel in disarray, shortly after Ukrainian President Volodymyr Zelenskyy announced deals with Western partners that would allow Kyiv to scale up drone production.

Between January and June, the number of Russian drone and missile attacks exceeded 23,000, a roughly 605% increase compared to the same period last year.