KIEV, March 1 (Xinhua) -- A massive airstrike conducted by Russian forces hit the center of Ukraine's second-largest city Kharkiv on Tuesday, the State Service for Emergencies said.

According to the agency, Russian rockets struck residential areas and buildings of the regional state administration.

On Monday, Russian troops shelled residential areas on the outskirts of Kharkiv, killing at least 11 civilians, according to Ukrainian authorities. Ukrainian President Volodymyr Zelensky called the shelling a "war crime."

Russia launched a "special military operation" against Ukraine on Feb. 24.