Russian airstrikes killed at least ten people and injured many others in a recreation area just outside Ukraine's northeastern city of Kharkiv on Sunday, local officials said.
"The explosions heard in Kharkiv around noon occurred in a nearby suburb. Two Russian missiles hit a recreation centre where people were relaxing, killing five people and injuring sixteen others," Kharkiv Mayor Ihor Terekhov said on the Telegram messaging app.
Reuters correspondents saw a recreation area destroyed after what rescuers at the scene said was a powerful blast, followed by a second, "double tap" strike about 15-20 minutes later.
Meanwhile, Ukraine fired nine US Army Tactical Missile Systems (ATACMS) at Crimea and attacked Russian regions with at least 60 drones in a major attack that forced one oil refinery in southern Russia to halt operations, Russian officials said on Sunday.
Russian air defences shot down nine ATACMS missiles over Crimea along with 57 drones over Russia's Krasnodar region and three drones over Belgorod region, the defence ministry said.
Local officials said six drones crashed onto the territory of an oil refinery in Slavyansk in Russia's southern Krasnodar region. Interfax news agency said the refinery halted work after the attack.
TASS quoted an official at the refinery as saying the charges carried by the Ukrainian-launched drones were bigger than previous attacks and that they included steel balls.
Slavyansk refinery is a private plant with a capacity of 4 million metric tons of oil per year, about 1 million bpd.
There was no immediate comment from Kyiv.