Russia denied firing missiles at a mall in the Ukrainian city of Kremenchuk, claiming instead that it had attacked a nearby storage facility for American and European weapons, setting off an explosion that started a fire inside the mall.

According to Ukraine, a deliberate Russian missile strike against the shopping center in Kremenchuk on Monday resulted in at least 18 fatalities. More over a thousand people were present, according to President Volodymyr Zelenskiy, when the rockets hit.

Russia’s defence ministry rejected Ukraine’s account, saying it had hit a legitimate military target in the city, and that the shopping centre was not in use.

Reuters was unable to independently verify the Russian account, or Zelenskiy’s claim that Russia intentionally hit the shopping centre to target civilians.

“In Kremenchuk, Russian forces struck a weapons depot storing arms received from the United States and Europe with high-precision air-based weapons,” Russia’s defence ministry said in a daily statement on the war.

“The detonation of stored ammunition for Western weapons caused a fire in a non-functioning shopping centre located next to the depot,” it added.

The G7 called the hit a Russian war crime, while Zelenskiy said it was “one of the most defiant terrorist attacks in European history”, accusing Russia of directly targeting civilians.

When asked about the attack on Kremenchuk, the Kremlin referred reporters to the defence ministry statement. Russia accuses Ukraine of carrying out attacks on civilians in Donbas.

Rescue efforts continued on Tuesday to recover survivors and bodies, with dozens reported injured and taken to hospital.

Ukraine has reported a sharp escalation in Russian attacks in recent days. On Sunday, a residential building in Kyiv was hit in the first attack on the capital since early June.

Alongside the shopping centre, Ukraine said Russian missiles also hit the eastern cities of Kharkiv and Lysychansk on Monday in one of the bloodiest days for civilian casualties in weeks.

Speaking hours after the first casualties were reported from Kremenchuk on Monday, Russia’s deputy ambassador to the United Nations, Dmitry Polyanskiy, accused Ukraine of using the incident to gain sympathy ahead of a June 28-30 summit of the NATO military alliance and pointed to “striking discrepancies” in Kyiv’s account of the incident.

Russia has repeatedly denied targeting civilian areas during its four-month offensive against Ukraine. The U.N. says at least 4,700 civilians have been killed since Russia invaded on Feb. 24.

President Vladimir Putin has repeatedly said that the main immediate reason for what he casts as a “special military operation” was to protect the Russian-speakers of Donbas from persecution and attack by Ukraine.

Ukraine and its Western backers say Russia is waging an unprovoked war against a sovereign state which is fighting for its existence. Kyiv says Russia’s claim of persecution of Russian-speakers is a baseless pretext for the invasion.

The conflict in eastern Ukraine began in 2014 after Russia annexed Crimea, with Russian-backed forces fighting Ukraine’s armed forces.

About 14,000 people were killed there between 2014 and 2022, when Russia invaded Ukraine, according to the Office of the U.N. High Commissioner for Human Rights.