Volodymyr Zelenskiy said more than 1,000 people were in the shopping centre at the time of the attack.
The toll from a Russian missile strike on a shopping mall in the central city of Kremenchuk has risen to 16 dead and 59 wounded, the head of Ukraine's emergency services said early Tuesday.
"As of now, we know of 16 dead and 59 wounded, 25 of them hospitalised. The information is being updated," Sergiy Kruk said on Telegram.
He said the main tasks were "rescue works, debris removal, and elimination of fires" following Monday's strike on the shopping centre.
Earlier, Zelensky had said "over a thousand civilians" were in the mall when the missiles struck the city, which had a pre-war population of 220,000 people.
"The mall is on fire, rescuers are fighting the fire. The number of victims is impossible to imagine," Zelensky wrote on Facebook.
A video shared by the Ukraine president showed the mall engulfed in flames with dozens of rescuers and a fire truck outside.
Emergency services also published images showing the smouldering remains of the building, with firefighters and rescuers trying to clear the debris.
The Ukrainian defence ministry said the strike was deliberately timed to coincide with the mall's busiest hours and cause the maximum number of victims.
The Ukrainian air force said the mall was hit by Kh-22 anti-ship missiles fired from Tu-22 bombers from the region of Kursk in western Russia.
"The missile fire on Kremenchuk struck a very busy area which had no link to the hostilities," the city's mayor Vitali Maletsky wrote on Facebook.
Lunin denounced the attack as a "war crime" and a "crime against humanity", saying it was a "cynical act of terror against the civilian population".
Ukrainian Foreign Minister Dmytro Kuleba called on Kyiv's allies to supply more heavy weapons and impose fresh sanctions on Russia.
"Russia is a disgrace to humanity and it must face consequences," he wrote on Twitter.
Presidential aide Mykhaylo Podolyak accused Russia of being a "terrorist state".
US Secretary of State Antony Blinken said, on Twitter, that "the world is horrified by Russia's missile strike today, which hit a crowded Ukrainian shopping mall -- the latest in a string of atrocities".
British Prime Minister Boris Johnson said the attack demonstrated the "depths of cruelty and barbarism" of Russian leader Vladimir Putin.
And the French foreign ministry also condemned the attack.
"By indiscriminately bombing civilians and civilian infrastructure, Russia continues its appalling violations of international humanitarian law," it wrote on Twitter.
"Russia must be held accountable for its actions."
(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)