Russian missiles struck the Ukrainian capital Kyiv on Sunday, a day after a key eastern city fell to pro-Russian forces in a major set-back for Ukraine and as world leaders gathered in Europe to discuss further sanctions against Moscow.

Up to four explosions rang out in central Kyiv in the early hours, in the first such attack on the city in weeks. Two more blasts were heard on the southern outskirts of the city later in the day, a Reuters reporter said.

“The Russians hit Kyiv again. Missiles damaged an apartment building and a kindergarten,” said Andriy Yermak, head of the president’s administration.

Ukraine’s police chief, Ihor Klymenko, said on national television that five people had been wounded.

As Europe’s biggest land conflict since World War Two entered its fifth month the Western alliance supporting Kyiv was starting to show signs of strain as leaders fret about the growing economic cost, including surging food and energy prices.

British Prime Minister Boris Johnson, speaking as Group of Seven leaders gathered for a summit in Germany, said the West needed to maintain a united front against Russian President Vladimir Putin.

“In order to protect that unity, in order to make it work, you’ve got to have really, really honest discussions about the implications of what’s going on, the pressures that individual friends and partners are feeling,” he told reporters.

“But the price of backing down, the price of allowing Putin to succeed, to hack off huge parts of Ukraine, to continue with his programme of conquest, that price will be far, far higher.”