A Russian missile struck a post office in Kharkiv on Oct. 21, killing six people and injuring at least 14, Kharkiv Oblast Governor Oleh Syniehubov said.
First responders are reportedly on site, and there is a rescue operation ongoing.
According to Syniehubov, several victims are in serious condition.
"This is an exclusively civilian object, the Russians committed yet another terror against the civilian population of Kharkiv region!" Syniehubov said.
Russian forces struck the city of Kharkiv with S-300 missiles on the evening of Oct. 21, Syniehubov reported earlier in the evening, urging residents to take shelter.
Kharkiv Mayor Ihor Terekhov confirmed that the city was under attack.
"Kharkiv hears explosions. The city is attacked by enemy missiles," Terekhov said.
Kharkiv, Ukraine's second-largest city, lies only around 30 kilometers south of the Russian border. Both the city and the surrounding oblast suffer regularly from Russian strikes.