KIEV - An explosion tore through an apartment building in southern Ukraine, killing at least 19 people and leaving dozens more trapped under the rubble, emergency officials said yesterday.

Up to 700 rescuers were searching for survivors in the wreckage of the collapsed five-story building in the Crimea peninsula resort of Yevpatoriya after a blast Wednesday caused by a suspected gas leak, the Emergency Situations Ministry said.

Some of those trapped called relatives on their cell phones pleading for a swift rescue but the calls stopped by midday local time, said a spokeswoman from the ministry's Crimea branch.

President Viktor Yushchenko and Prime Minister Yulia Tymoshenko were flying to Yevpatoriya, according to their Web sites.Russian President Dmitry Medvedev offered to send naval personnel from Russia's Black Sea fleet, stationed at the Ukrainian port city of Sevastopol, to help with the rescue, a Kremlin spokesman said.