Four newborn babies were killed in the intensive care unit of the Giulesti maternity hospital in Bucharest on Monday, in an explosion caused by an electrical fault, people close to the matter said, Romanian Mediafax news agency reports.

Seven other babies were severely burnt in the explosion apparently caused by a glitch in the hospital's air-conditioning system, said Health Ministry undersecretary Raed Arafat, also chief of the emergency services.

Arafat said rescuers discovered the injured babies in the intensive care department, adding they had been sent to the Bucharest Grigore Alexandrescu children hospital, while their mothers were admitted to other medical units.

Dan George Enescu, head of the Grigore Alexandrescu hospital, described the babies' condition as "extremely critical" and said prematurely born babies have burns covering 70-80%t of their bodies, which, he stressed, it is too much for them.

Prosecutors set off an investigation to establish what caused the explosion and whether it is a negligence case.

An explosion took place Monday afternoon at the Intensive Care section of the Giulesti Maternity Ward in Bucharest. By Tuesday morning, four newborns died and another seven were in serious condition. During the intervention, 113 people were evacuated from the hospital, 53 of which were children. The wounded babies suffered serious burns in the incident.

Health minister Cseke Attila and ministry state secretary Raed Arafat said in a press conference on Tuesday that all intervention procedures to evacuate the hospital in the fire were correct. But no resignation was announced. The statements came as authorities failed to provide media statements during the evening and the night. On Tuesday, they argued that they could not do so because they did not exact data to share and the families of the newborns who died following the incident had to be informed about it first.

For his part, a top prosecutor said at noon on Tuesday that they could not say the precise causes of the Giulesti ward accident. He said that the nurse on duty at the time of the fire was in state of shock and that a criminal in rem inquiry had started