KYIV, Ukraine — Russian attacks targeting the eastern Ukrainian city of Kharkiv killed at least four people and wounded more than two dozen others Saturday, officials said, as hopes for peace dimmed further.

The first wave on Ukraine’s second-largest city was a large Russian drone-and-missile attack in the early hours. It killed at least three people and wounded 21 others, according to local officials.

In the afternoon, Russia dropped aerial bombs on the city, killing at least one person and injuring five more, Kharkiv’s mayor said.

The warring sides also accused each other of trying to sabotage a planned prisoner exchange, nearly a week after Kyiv embarrassed the Kremlin with a drone attack on military airfields deep inside Russia.

Saturday’s barrage — the latest in near daily wide-scale attacks on Ukraine — included aerial glide bombs that have become part of a fierce Russian onslaught in the all-out war, which began Feb. 24, 2022.

Kharkiv resident Vadym Ihnachenko said he thought at first that it was a neighboring building going up in flames. “But when we saw sparks coming from the top, we realized it was our building,” he said.

Ukraine’s air force said that Russia struck with 215 missiles and drones overnight, and Ukrainian air defenses shot down 87 drones and seven missiles.

Several other areas in Ukraine were also hit, including the regions of Donetsk, Dnipropetrovsk and Odesa, and the city of Ternopil, Ukrainian Foreign Minister Andrii Sybiha said in a post on X.

“To put an end to Russia’s killing and destruction, more pressure on Moscow is required, as are more steps to strengthen Ukraine,” he said.

The Russian Defense Ministry on Saturday said that its forces carried out a nighttime strike on Ukrainian military targets, including ammunition depots, drone assembly workshops and weaponry repair stations. There was no comment from Moscow on the reports of casualties in Kharkiv.

Later on Saturday, Russia and Ukraine each accused the other of endangering plans to swap 6,000 bodies of soldiers killed in action, agreed upon during direct talks Monday in Istanbul that otherwise made no progress toward ending the war.

Vladimir Medinsky, a Putin aide who led the Russian delegation, said that Kyiv called a last- minute halt to an imminent swap. In a Telegram post, Medinsky said that refrigerated trucks carrying more than 1,200 bodies of Ukrainian troops from Russia had already reached the agreed exchange site at the border when the news came.

In response, Ukraine said Russia was playing “dirty games” and manipulating facts.

According to the main Ukrainian authority dealing with such swaps, no date had been set for repatriating the bodies. In a statement Saturday, the agency also accused Russia of submitting lists of prisoners of war for repatriation that didn’t correspond to agreements reached Monday.

It wasn’t immediately possible to reconcile the conflicting claims.