The number of deaths in a natural gas explosion that rocked an apartment building in eastern Ukraine went up to 15 on Monday, though rescue workers continued searching for more people possibly buried under the rubble.
The blast on Saturday destroyed much of the 10-story building in the industrial city of Dnipropetrovsk, about 600 kilometers (370 miles) from the capital, Kiev, ripping off parts of the roof and blowing out dozens of windows.
The blast was so powerful that the shock wave damaged several other multistory apartment buildings and small houses in the vicinity.
Seventeen people, including three children, remained hospitalized Monday, while others were still missing and may be buried beneath the debris, said Lyudmila Shcherban, a spokeswoman for the Emergency Situations Ministry.
Investigators were working to determine the cause of the blast. Shcherban said one possibility was a sharp increase in pressure in the city's gas pipes.
Prosecutors later said on their Web site that two senior managers at Dniprogaz, the gas operator in Dnipropetrovsk, had been arrested on suspicion of negligence in the incident. The statement gave no details.
President Viktor Yushchenko called for a day of mourning for the victims on Tuesday.
Natural gas explosions resulting from improper usage, poor infrastructure or faulty butane and propane tanks are common in the former Soviet Union.