A gas explosion, named as a preliminary cause of a collapse at night in Drohobych of Lviv region, of the entrance of a four-story apartment building is unlikely, the State Emergency Service of Ukraine reported.

"At first, there was a suspicion that a gas explosion took place, but during the works and operations of the gas service it was found this is unlikely," said Petro Korotynsky, deputy director of the State Emergencies Service's Response Department, at a briefing in Kyiv on Wednesday morning.