At least 18 people have died in a missile strike on a shopping centre in the Ukrainian city of Kremenchuk.
Some 1,000 civilians were estimated to be inside the busy mall at the time of the attack at around 15:50 (12:50 GMT), President Volodymyr Zelensky said.
The leaders of the G7 group of richest nations - who are meeting in Germany - condemned the attack as "abominable".
"Indiscriminate attacks on innocent civilians constitute a war crime," they said in a joint statement.
Russia has been blamed for the attack, which also injured at least 59 people, and there are fears the death toll will continue to rise.
Pictures online showed the building engulfed in flames and thick black smoke billowing into the sky.
He said the mall had no strategic value to Russia and posed no danger to its forces - "only the attempt of people to live a normal life, which so angers the occupiers".
"Only totally insane terrorists, who should have no place on earth, can strike missiles at such an object," he added.
Russia's Deputy Ambassador to the UN, Dmitry Polyanskiy, called the attack a "Ukrainian provocation", but cited no evidence to suggest that the missile strike had been staged.
The local governor, Dmytro Lunin, described the attack as a crime against humanity, writing on Telegram that is was "an obvious and cynical act of terror against the civilian population".
Authorities say 440 people from emergency services are working on location, including 14 psychologists brought in to support those affected.
Photos from the scene show the blackened and charred shell of the building with the roof caved in.
In one video taken shortly after the strike, a man can be heard calling out: "Is anybody alive… anybody alive?" Soon after, ambulances arrived to take the injured to hospital.
But there are still people missing and as night fell, family members gathered at a hotel over the road, where rescue crews have set up a base to wait for any news. Lights and generators have been brought to the site so crews can continue the search overnight, Reuters news agency reports.
The central-eastern city of Kremenchuk is located about 130km (81 miles) from Russian areas of control.