- Ukraine is on the defensive after Russian forces took control of the eastern town of Avdiivka last month.
- The commander-in-chief of the armed forces has signalled he will replace some military leaders on the eastern front.
Ukrainian President Volodymyr Zelensky had called on the West to deliver more air defence systems after at least five people died in a strike on Odesa.
A three-year-old was among those killed by a Russian drone in the southern city, officials said. Two other people died in strikes elsewhere in Ukraine.
"Russia continues to wage war on civilians," President Zelensky said.
Ukraine is on the defensive after Russian forces took control of the eastern town of Avdiivka last month.
The commander-in-chief of the armed forces has signalled he will replace some military leaders on the eastern front.
In a post on Telegram on Saturday, Interior Minister Ihor Klymenko said a nine-storey building had been destroyed as a result of "an attack by Russian terrorists" in Odesa.
Footage from the scene showed that several floors of a residential building had been destroyed.
At least five people, including the three-year-old child, were killed, eight were wounded and several are still unaccounted for, officials said.
Separately, they said that one person had been killed in the Kharkiv region near the Russian border and another in the southern Kherson region.
In a post on social media, Mr Zelensky said: "We need more air defences from our partners. We need to strengthen the Ukrainian air shield to add more protection for our people from Russian terror. More air defence systems and more missiles for air defence systems saves lives."
Ukraine's air force said it had downed 14 or 17 drone launched by Russia overnight.
Russian forces have has launched thousands of Iranian-made drones at Ukrainian targets since they invaded Ukraine over two years ago.
In retaliation Ukraine has targeted Russian sites, notably oil facilities.
On Saturday a drone struck a residential building in St Petersburg, Russia's second-largest city. About 100 people were evacuated and there are no reports of casualties, officials say.
Some Russian media said the incident could have been caused by a downed Ukrainian drone, which was heading towards a fuel depot. There has been no official confirmation of this from the Kremlin.
The full-scale invasion of Ukraine launched by Russian President Vladimir Putin is now in its third year.
Early on Saturday, the commander-in-chief of Ukrainian forces, Gen Oleksandr Syrskyi, signalled that he would replace some commanders on the eastern front.
The move comes after the fall of Avdiivka, which marked the biggest change on front line since Russian troops seized the nearby town of Bakhmut in May 2023.
Avdiivka was engulfed in fierce fighting for months. This week, Ukraine's military withdrew from two nearby villages, losing more territory as the supply of weapons and ammunition from its Western allies ran short.
Gen Syrskyi said he would change those commanders whose orders and actions had threatened the lives of troops.
He wrote on Telegram: "I have sent groups of specialists to individual brigades where there are problems with the preparation of the headquarters to transfer experience and provide assistance."
Gen Syrskyi praised some brigades, and promised - after listening to front-line units - to provide reserves, ammunition and expertise to back them up.
He insisted the situation on the front line "remains difficult, but controlled".
President Zelensky sacked Gen Syrskyi's predecessor, Valerii Zaluzhnyi, less than a month ago.