Three Russian missiles hit a residential building and two resorts in Serhiivka village, Odesa Oblast, on the night of July 1, local authorities reported citing the Ukrainian military.
At least 19 people were killed as of 12 p.m. on July 1.
The attack on the nine-story residential building killed 16 people, while 34 others were injured, including five children, Deputy Head of the President's Office Kyrylo Tymoshenko reported.
Two people, including a 12-year-old boy, were killed in the attack on one of the resorts, according to Tymoshenko. Five more were injured there.
Two children and one adult remain under the rubble of the resorts, Tymoshenko reported.
According to Odesa Oblast Governor Maksym Marchenko, 31 people were hospitalized, including four children and a pregnant woman. Rescue operations are ongoing.
The attack took place at around 1 a.m. on July 1. According to Marchenko, Russia’s Tu-22 strategic bombers launched three Kh-22 anti-ship missiles from the direction of the Black Sea.
Odesa Oblast administration spokesman Serhii Bratchuk said that a warhead of such a missile alone weighs almost a ton, adding that Russia has many such rockets.
Tymoshenko reported that the residential building and one of the resorts were "destroyed completely."
Around 150-160 people lived in the nine-story building, according to Bratchuk.
No details have yet been published about the second resort attacked.
During the past few days, Russia has increased its missile strikes hitting both civilian and military targets all over Ukraine.
On June 26, Russia launched missiles at Kyiv for the first time in nearly three weeks, hitting a residential building and a kindergarten, and killing one person and injuring six others, including a seven-year-old child, as a result.
On June 27, a Russian missile strike hit a shopping mall in the central Ukrainian city of Kremenchuk, killing at least 20 people and injuring 59 others.