About 200 rescuers resumed their work on clearing the debris of the caved ice rink in Bad Reichenhall on Wednesday, with the aid of cranes and excavators. But hopes were fading of finding the remaining woman trapped under its collapsed roof alive.

The district attorney's office has meanwhile begun an investigation into negligent manslaughter. But the criminal investigation department in Traunstein responsible for the case declined to release any details of the reasons behind the tragedy, which has killed 14 people, mostly children and youth.

"It would be pure speculation at this point to say anything about the cause of the accident," said police chief Hubertus Andrä. State prosecutor Helmut Vordermayer said evidence was being collected and a probe into the accident had been opened.

Was it just the snow?

Many people, both in the region and across the country, are asking themselves how such an accident could have happened. Germany is, after all, well known for its precision engineering and strict regulations.

It is currently not clear what caused the flat roof of the building, which dates from the 1970s, to cave in on Monday afternoon. The region is accustomed to heavy snowfall, which some say possibly triggered the roof's collapse.

But there are also reports of inadequate maintenance of the facility and the authorities' delayed decision to evacuate the rink, just minutes before the roof collapsed.

The rink was operated by the city. Bad Reichenhall's mayor Wolfgang Heitmeier has rejected allegations of negligence for allowing the rink to remain open. He said the roof had been examined late Monday morning to determine whether it could withstand the weight of the snow.

Heitmeier told reporters the amount of snow was far below the specified limit. He rejected speculation that the authorities knew of structural problems. Heitmeier said he "could not explain" what caused the collapse.

Roof's construction possibly faulty

Structural engineer Hubert Widmann from the Examination Office for Structural Analysis in Munich said the snow alone could not have triggered the accident.

"The 30 to 40 centimeters of snow that was on the roof before the collapse could not have caused these catastrophic results alone," Widmann told Bavarian radio Bayern 2.

Engineer Markus Rapolder told sister station Bayern 1 that the roof should have been able to hold the snow masses.

"The amount of snow only plays a role when a roof's construction is defective," Rapolder said. He said that the weight of the snow was more critical than the amount.

"There is light powder snow and heavy sticky snow," Rapolder said. "If I know that a roof is defective, you should calculate the actual weight of the snow."

"The problem is that there is no legal obligation to control public buildings for damage in the roof construction," said Rapolder. This was only the case for bridges. "So you can only hope that owners are informed about possible defects."

Further buildings cave in from snow

The ongoing snowfall has caused further damage in other parts of the region. A supermarket collapsed in the Czech Republic Tuesday evening, injuring one person.

Also on Tuesday, the roof of a warehouse in Aying near Munich collapsed under the weight of the snow. No one was injured. In Salzburg, Austria, the roof of a bowling alley caved in. No one was injured there, either.