A malfunction in the gas distribution system was the cause of Saturday's gas explosion in an apartment building in eastern Ukraine, the country's gas company Dniprogaz said Sunday.
An emergency committee was investigating the cause of the malfunction, Dniprogaz Director Ihor Ivankov was quoted by the Interfax news agency as saying in Dnipropetrovsk, some 600 km away from Kiev.
Rescuers were still looking for more than 20 people who could have been trapped inside the building, home to about 400 people, Interfax said.
An explosion ripped through an apartment building in the industrial city of Dnipropetrovsk Saturday, causing 13 deaths and injuring 25 others.
Part of the ten-storey building was destroyed, and nearby buildings were also damaged due to strong shock waves sent by the powerful blast.