KYIV, Ukraine (AP) — A missile strike on a mail depot in the eastern city of Kharkiv killed six people, Ukrainian officials said Sunday, as Ukraine reported a record number of bomb attacks in the southern Kherson region.

A further 17 people were wounded in the blast late Saturday, which is believed to have been caused by a Russian S-300 rocket, Kharkiv Gov. Oleh Syniehubov said on social media. All of the victims were employees of private Ukrainian postal and courier service Nova Poshta.

The Ukrainian-held front-line city has been at the heart of fierce fighting as both Moscow and Kyiv push fo...