Russian forces in Ukraine are bombing cities and killing civilians, but they are no longer making ground progress, Western countries said on Thursday, as a war Moscow had hoped to win in days entered its fourth week.

Rescuers in the besieged southern port of Mariupol were combing the rubble of a theatre where women and children had been sheltering, which had been bombed by Russian forces the day before.

“The bomb shelter remained intact. The rubble is now being removed. There are a few survivors. We do not yet know the (number of) victims “Petro Andrushchenko, a mayoral adviser, told Reuters by phone.

Russia denied striking the theatre, which commercial satellite pictures showed had the word “children” marked out on the ground in front before it was blown up.

Mariupol has suffered the worst humanitarian catastrophe of the war, with hundreds of thousands of civilians trapped in basements with no food, water or power for weeks. Russian forces have begun letting some people out in private cars this week but have blocked aid convoys from reaching the city.

Viacheslav Chaus, governor of the region centred on the frontline northern city of Chernihiv, said 53 civilians had been killed there in the past 24 hours. The toll could not be independently verified.

In the capital Kyiv, a building in the Darnytsky district was extensively damaged by what the authorities said was debris from a missile shot down early in the morning.

As residents cleared glass and carried bags of possessions away, a man knelt weeping by the body of a woman which lay close to a doorway, covered in a bloody sheet.

Although both sides have pointed to limited progress in peace talks this week, President Vladimir Putin, who ordered Russia’s invasion on Feb. 24, showed little sign of relenting.

In a vituperative televised speech, he inveighed against “traitors and scum” at home who helped the West, and said the Russian people would spit them out like gnats.

Dmitry Medvedev, deputy head of Putin’s security council, said the United States had stoked “disgusting” Russophobia in an attempt to force Russia to its knees: “It will not work – Russia has the might to put all of our brash enemies in their place.”

Kyiv and its Western allies believe Russia launched the unprovoked war to subjugate a neighbour Putin calls an artificial state. Moscow says it is carrying out a “special operation” to disarm and “denazify” Ukraine.

Heavily outnumbered Ukrainian forces have prevented Moscow from capturing any of Ukraine’s biggest cities so far despite the largest assault on a European state since World War Two. More than 3 million Ukrainians have fled and thousands of civilians and combatants have died.