Mykolaiv mayor Oleksandr Syenkevych shared the details in his Telegram channel.
"In the morning, Russian forces fired rockets at Mykolaiv," he wrote.
Rescuers, medics, emergency teams and utility workers are already working at the scene.
The explosions were heard at 7:00, before the air raid warning.
Syenkevych clarified the consequences of the morning strikes on the city: 7 high-rise buildings were damaged, and there were victims.
"Residential buildings were damaged again due to the shelling. More than 200 windows in 7 high-rise buildings were broken by the blast wave and debris, entrance doors were damaged in the entrances, people had to cut the locks in some apartments to get out," he wrote.
Some residents received minor injuries, they refused medical assistance, added the mayor.