Ukrainian officials said Russian airstrikes on the country’s second-largest city, Kharkiv, early Monday destroyed a school and a residential building, killing at least three people and wounding 28 others.

Oleh Syneihubov, governor of the Kharkiv region, said on Telegram that the missile strikes, which also included one that landed near warehouse facilities, were launched against civilian targets. Syneihubov called the attacks “absolute terrorism.”

The strikes came as rescuers in the eastern town of Chasiv Yar worked to find any survivors from a Russian rocket attack on a five-story apartment building Saturday that killed at least 15 people.

Emergency services personnel said there may be as many as two dozen people trapped in the rubble, and that they had made voice contact with several.

Chasiv Yar is about 20 kilometers southeast of Kramatorsk, a city that is expected to be a major target of Russian forces as they push farther westward into Donetsk province after claiming victory a week ago in the adjoining Luhansk province.

The Chasiv Yar attack was the latest strike in recent weeks that left mass civilian casualties, although Russia contends it only targets Ukrainian military operations. A late June attack killed at least 19 people at a shopping mall in Kremenchuk, and an attack on an apartment building and recreation area in the southern Odesa region killed 21 this month.

Some information in this report came from The Associated Press and Reuters.