KYIV, June 14 (Reuters) - Russian missiles struck civilian buildings in Ukraine's Black Sea port of Odesa and eastern Donetsk region overnight, killing at least six people, Ukraine's military and local officials said early on Wednesday.

Russia launched four cruise missiles on the city of Odesa, the South command of Ukraine's Armed Forces said. The military said earlier that two missiles were destroyed before hitting their targets.

"As a result of air combat and blast waves, a business centre, an educational institution, a residential complex, food establishments and shops in the city centre were damaged," the South command said on the Telegram messaging app.

The three people killed were working at a retail chain's warehouse when a missile hit, setting it ablaze, the military added. Seven people were wounded there.

"Sifting through the debris continues," the military said. "There may be people under."

Serhiy Bratchuk, a spokesman for the Odesa military administration, posted a video and photographs showing multi-storey buildings with parts of their walls missing and windows blown out, as well as firefighters battling against flames in what it appeared be a warehouse.

In a separate missile strike, Russian forces killed three civilians in Ukraine's eastern Donetsk region, the governor Pavlo Kyrylenko said on Facebook.

He said two people were killed in Kramatorsk and another in Kostiantynivka.

"The missiles ... hit private houses in the cities and caused significant damage: in Kramatorsk, at least 5 private houses were destroyed and about two dozen damaged, in Kostiantynivka, two were destroyed and 55 damaged," he said.

Ukrainian Air Forces said they destroyed three missiles and nine drones overnight.

Reuters could not independently verify the reports. There was no immediate comment from Russia. Both Russia and Ukraine deny targeting civilians in their military operations.