A commission investigating an explosion in an apartment building in Kharkiv has found out that a gas cylinder, which was improperly filled at a petrol station, was behind the blast.

"A commission holding an inquiry into the causes and technical reasons for the accident... has found that a cylinder with liquefied gas that exploded in the residential building, was filled at a petrol station with gross violation of health and safety regulations," reads a report posted on the Web site of the State Service of Mining Supervision and Industrial Safety on Wednesday.

The service stressed that after the cylinder, which was filled with liquefied gas at low temperature, was brought into a warm room there was an abrupt expansion of the gas, which triggered the destruction of the cylinder and the formation of an explosive gas-air mixture.

As reported, on December 16, an explosion and fire occurred at a 16-storey residential building in Kharkiv, which killed four people (including an 11-month-old child), eight were hospitalized.

The blast destroyed separating walls, damaged ceilings and floors between the ninth, tenth and eleventh floors, and the facade of the building was also damaged. Fire destroyed four walls.