South Korea is reporting that a 23 storey apartment building has collapsed in the North Korean capital Pyongyang.
North Korea has confirmed what it is calling an unimaginable accident and said there were casualties.
It is extremely rare for North Korea to report negative news of this type, and its official Korean Central News Agency (KCNA) said the accident was the result of irresponsible supervision by officials in charge of construction.
The accident was reported on Sunday morning by KCNA and the report said it occurred in the Phyongchon district on Tuesday.
South Korean officials said the apartment building was on a construction site but already accommodated close to 100 families.
A South Korean official said it was common in North Korea that people moved into a new apartment building before construction officially ended.
An official said 92 families were believed to be living in the collapsed building, and the final death toll was likely to be "considerable".
AFP reports that about 2.5 million people - mostly political elites including senior party members or those with privileged background - are believed to live in Pyongyang.