A landslide in Norway, 25km north-east of capital Oslo buried homes under dark mud injuring 10 people and leaving 11 missing.
While rescue workers continue to search for the missing in Gjerdrum village, 900 people have been rescued.
“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 told reporters.
The landslide began during the early hours of Wednesday, with residents calling emergency services and telling them that their houses were moving, police said.
Prime Minister Erna Solberg said the situation was still so unstable that only rescues by helicopter could be carried out.
“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,” she told reporters.
“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, a local resident told local news.
“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.”
Large quantities of earth were continuing to move, Toril Hofshagen, the regional head of the Norwegian Water Resources and Energy Directorate (NVE), told reporters.
The local municipality warned that up to 1,500 people could need to leave the region because of concerns about the condition of the ground.
An NVE spokeswoman told AFP that the landslide was a so-called “quick clay slide” measuring about 300m by 700m.
“This is the largest landslide in recent times in Norway, considering the number of houses involved and the number of evacuees,” Laila Hoivik said.
Quick clay is a kind of clay found in Norway and Sweden that can collapse and become fluid when it comes under stress.
However Ms Hoivik said further slides were unlikely.
Broadcaster NRK said heavy rainfall may have made the soil unstable.
Norway’s King Harald, 83, said that the incident had “made a deep impression on me and my family”.
“My thoughts are with everyone affected, the injured, those who lost their homes and are now living in fear and uncertainty of the full extent of the disaster,” he said in a statement released by the royal palace.