Ten people were injured, one critically, and 11 were missing after a landslide in southern Norway swept away more than a dozen buildings early on Wednesday, police said.
The landslide struck a residential area in the municipality of Gjerdrum, about 30 kilometres north of the capital Oslo.
Police said more than 900 people had been moved to safety from the area.
Rescue workers continued to search the area for children and adults who were feared to have been caught in mud and debris, police said.
"We are quite certain that there are people in the affected area, but we don't know if all 11 are there or if the number is smaller," police spokesman Roger Pettersen said.
"We're still searching for survivors."
Photos of the site showed a large crater with destroyed buildings at the bottom. Other buildings hung on the edges of the crater, TV footage showed.
Two more houses collapsed into the hole on Wednesday afternoon, broadcaster NRK reported.
Norway's King Harald told of his sorrow for victims of the landslide.
"My thoughts are with all those who are affected, injured or have lost their homes and those who now live in fear and uncertainty of the full extent of the catastrophe," said King Harald, 83.
As night fell, helicopters continued to hover over the area, at times lowering emergency responders to the debris of collapsed houses.
"There could be people trapped ... but at the same time we can't be sure because it is the New Year's holiday, which means people could be elsewhere," Prime Minister Erna Solberg said after visiting the site.
Local residents told of their experience.
"There were two massive tremors that lasted for a long while and I assumed it was snow being cleared, or something like that," Oeystein Gjerdrum, 68, told NRK.
"Then the power suddenly went out, and a neighbour came to the door and said we needed to evacuate, so I woke up my three grandchildren and told them to get dressed quickly."
Masses of earth are still moving in one of the largest clay slides in recent Norwegian history, said Toril Hofshagen, the regional head of the Norwegian Water Resources and Energy Directorate.