Following the blast, police investigators detained a gas technician who worked at the building the day before. Police said that their preliminary investigation revealed that the technician only performed a temporary fix of the problem.
The technician, an employee of the gas company Supergas, has been detained on suspicion of negligence, and further investigations will take place on Monday afternoon.
'Supergas' released a statement: "according to our records, a complaint was received from the site of the explosion at 22:15 Sunday night. The technician reportedly shut the gas taps. Unfortunately, the explosion took place later that night."
"The gas piping, according to the law, must be checked every five years. Our last recorded check-up was in December 2012 and the gas network was found to be functioning properly.
We will cooperate fully with the police and security officials to get to the bottom of this investigation," added 'Supergas' spokesperson.