Further demolition work will be required to determine the cause of a deadly hotel collapse in the western German town of Kröv last week, local authorities said on Monday.

A police spokesman said surveyors from the local building authority were also still inspecting the rubble.

"It's going to take a while yet," he said.

An entire floor of the hotel on the picturesque Mosel river, a popular tourist destination famous for its vineyards, collapsed late in the night of August 6. 

Two people – a 64-year-old woman and the 59-year-old hotel owner – were killed, and seven more people were eventually rescued from the rubble.

One of those, a 26-year-old father from the Netherlands, was taken to hospital in the nearby in the nearby German city of Trier with serious injuries and put into an induced coma. "His condition is not good," a police spokesman said on Sunday evening.

On Monday, he was flown to a specialist clinic in the Netherlands where he will be operated on.

Crowdfunding campaign raises €50,000

The man's 23-year-old wife, who was pulled from the rubble unharmed along with the couple's two-year-old son, wrote on social media that her husband was half-awake and that they had been able to communicate.

She said he was in a stable condition for the time being but that the doctors had warned that this could change, and asked people to pray for him.

Family members spoke via video link at a church service in Kröv on Sunday during which they thanked the emergency services. "We trust that he'll recover," said the man's father. "The doctors are good."

Meanwhile, a crowdfunding campaign in the Netherlands has raised over €54,000 ($59,000) to help cover the cost of the flight transfer and further treatment.

According to Dutch media, the family's insurance does not cover this sort of emergency abroad.

Hotel structure dates to the 17th century

Back in Kröv, investigations are also underway into damage sustained by neighboring buildings, including small tears in walls which appear bigger since the collapse.

According to local fire and catastrophe protection inspector Jörg Teusch, the basic foundations of the collapsed hotel date from the 17th century.

The building originally had wooden ceilings, but concrete ceilings were installed when two new floors were added in 1980.

Teusch said the investigations will show "whether something went wrong in the substructure of the building."

mf/wmr (dpa, AFP)