MOSCOW, December 26 (RIA Novosti) - The number of dead from a gas explosion in an apartment building in southern Ukraine has risen to 27, including three children, local media said on Friday.

The powerful blast ripped through the five-story apartment block in a quiet suburb of the resort town of Yevpatoriya late Wednesday. According to preliminary information, oxygen containers kept in the basement may have exploded.

Ukraine's Channel 5 TV station reported on Friday that 27 people had been confirmed killed in the blast, although the emergencies ministry said the bodies of 26 people had been pulled from the debris.

A total of 21 people have been rescued from the rubble, and five of them have been hospitalized.

The rescue operation, involving 565 people, is continuing. The number of people missing is unknown, but authorities said fatalities could rise further as it is feared more victims are trapped under the remains of their building.

Friday has been declared a day of mourning for those killed in the incident.

The explosion destroyed 33 flats in the central section of the house where a total of 58 people were registered inhabitants, and also damaged a number of other flats. Some 1,600 metric tons of debris has been removed from the scene.

Ukrainian Prime Minister Yulia Tymoshenko, who made a personal visit to Yevpatoriya on Thursday, promised compensation to those injured and the families of the killed. She said $12,800 would be paid for every victim, while those left homeless would be given new housing later this year.

Ukraine's President Viktor Yushchenko also visited the scene. The government has already allocated $9 million to help those affected by the deadly blast.

Russian President Dmitry Medvedev offered Kiev on Thursday the services of the Black Sea Fleet to help deal with the explosion.