Prague, July 17 (CTK) – Two floors collapsed in a building under reconstruction in Mikulandska street in the centre of Prague Tuesday morning, burying several people, three of whom have been found with severe injuries and rescued by firemen, who, however, do not know how many people may still stuck under the ruins.

The rescue operation is extremely demanding since the building, which is being adapted for the purposes of the Academy of Arts, Design and Architecture (UMPRUM), may collapse anytime.

By sunset, the firefighters removed some 70 percent of the debris, which increased the probability that no one else remains buried underneath, their commander Oldrich Klegr told reporters.

He said the intervention will continue in the night until all debris is removed.

Arriving at the scene of the accident earlier on Tuesday, Prague Mayor Adriana Krnacova said the National Heritage Institute (NPU) might have forced the reconstruction authors into applying far-from-standard methods.

The NPU has rejected the suspicion as absurd.

The accident occurred around 10:30. Its cause is yet to be ascertained.

Three persons were pulled out of the debris during the first hours of the rescuers’ intervention and treated by an emergency service staff for serious injuries. The firefighters are looking for other missing persons, whose number they put at two to four earlier on Tuesday.

Dogs repeatedly confirmed that there might be other people alive under the debris.

One of the rescued persons is in a very serious condition and must be kept in induced sleep, Prague emergency service spokeswoman Jana Postova said. The condition of the other two is less serious, she added.

Five fire corps units, emergency service personnel, police officers and dog handlers of the municipal police are assisting on the spot. A special excavator is used for removing debris. Psychologists, a structural engineer, labour inspectors and experts from the mining service were also sent to the scene of accident.

“Three people have been rescued and firefighters are searching for others,” Prague police spokesman Jan Rybansky said earlier on Tuesday, adding that up to another four might be in the debris, while rescuers spoke about another two.

Firefighters built a provisional protection against another collapse. However, they say this risk still exists.

The cause of the accident will be investigated after the rescue operation.

The Metrostav company, which is reconstructing the building, ruled out that any work safety regulations were violated at the construction site.

“The ceiling collapse will be duly investigated,” Metrostav spokesman Martin Patricny said. However, he did not say how many people were working at the building site.

Krnacova (ANO) told reporters that it is necessary to “look into the role of designers and primarily the role of heritage protectors from the National Heritage Institute, which forced the designers into what might have been non-standard methods [of reconstruction].”

The Prague 1 building office will have to say whether the technological procedure has been observed in this case, she added.

Dismissing Krnacova’s words as absurd, the NPU said its steps have always been standard and in harmony with the heritage protection law.

The NPU has a say on the reconstruction design since the building in question is situated in the UNESCO-listed historical centre of Prague.

The traffic on the nearby main Narodni street was partially restricted over the accident.

The building where two storeys tumbled down used to be a primary school. After the reconstruction, it will house a technological centre and workshops for students of the UMPRUM Academy.