Six people have been killed and a further 14 injured after a missile hit a postal distribution centre in eastern Ukraine late on Saturday night.
Ukrainian President Volodymyr Zelensky said on Telegram the Nova Poshta sorting office was struck in Kharkiv.
Pictures from the scene posted on President Zelensky's account showed the building with windows blown out.
Kharkiv's regional governor Oleh Syniehubov said the private delivery company was "strictly a civilian site".
"The Russians have inflicted more terror on Kharkiv's peaceful population," he wrote in his own Telegram post.
President Zelensky added that a rescue operation was continuing, with emergency services working at the scene.
Russia has not yet commented on the alleged strike, but has previously denied targeting civilians during its invasion of Ukraine.
Syniehubov said all six people killed and 14 others injured were Nova Poshta terminal employees.
Kharkiv, which is Ukraine's second largest city, is located only 30km from the Russian border.
The north-eastern city was heavily bombed during the first weeks of the war in February 2022.
Earlier this month, Kharkiv Mayor Ihor Terekhov said Ukraine's first underground school would be built in the city to allow children to continue in-person education safely.
Meanwhile in the south, Ukraine has been waging a counter-offensive campaign since June.
The war-torn country aims to sever Russia's land corridor to the Crimean peninsula - which Russia illegally annexed in 2014.
But the counter-offensive has so far proven slow, bringing only limited territorial gains.
- this story was originally published by the BBC