North Korea said a "serious" accident last week at a construction site in the capital, Pyongyang, claimed casualties and triggered a major rescue operation but no death toll was mentioned.
The accident was reported Sunday morning by the official Korean Central News Agency.
The report said it occurred in Phyongchon district on Tuesday "as the construction of an apartment house was not done properly and officials supervised and controlled it in an irresponsible manner."
According to the KCNA report, the rescue operation ended Saturday and officials apologized to bereaved families and district residents.
The report cited one official as saying North Korea's leader Kim Jong Un "sat up all night, feeling painful after being told about the accident."
The highly controlled state media for the reclusive regime rarely report news that might be considered negative.