WARSAW, Poland — The deadly collapse of an apartment block in the western Polish city of Poznan was probably caused by a resident who had killed his wife and then tried to kill himself by opening gas valves that caused an explosion, according to Poland’s state news agency PAP.

The news agency reported Tuesday that the man remains hospitalized with severe burns and cannot be questioned by prosecutors. PAP quoted anonymous sources that it says are close to the investigation.

Prosecutors contacted by phone on Tuesday refused to confirm the information. They said previously that the building’s collapse could have been triggered by a gas explosion and that the incident may not have been an accident.

Five people were found dead in the rubble and 21 others were injured in Sunday’s explosion.