Russian regional and Ukrainian officials reported that attacks on Monday killed 26 people, with 15 deaths reported in Russia and 11 in Ukraine.
Krasnodar Governor Veniamin Kondratyev said a Ukrainian drone strike killed seven people, including three children, in the resort settlement of Arkhipo-Osipovka.
Kondratyev said about 40 people were injured there.
Russian authorities also reported four deaths and two injuries in Crimea, and four deaths with at least 17 injuries in Belgorod region, in Ukrainian attacks.
Ukrainian officials said a Russian drone struck a petrol station in the Kryvyi Rih district of Dnipropetrovsk region, killing three people.
Those killed at the petrol station included an emergency-service worker and his eight-year-old son, officials said.
Dnipropetrovsk Governor Oleksandr Hanzha said the strike caused a fire and damaged the station and surrounding area.
Ukrainian officials said a later Russian drone and missile attack in Zaporizhzhia killed eight people, including two children.
Russia's Defence Ministry separately claimed that its forces had captured Bilyi Kolodiaz and Uspenivka in Kharkiv region.
Both Russia and Ukraine have denied targeting civilians.