Thirteen people have now been confirmed dead in a building collapse early Thursday morning in Beian City in northeast China's Heilongjiang Province.
Six injured have been hospitalized, and three others are still missing.
The building, part of a local elementary school, was under renovation when it collapsed around 7:40 a.m. Thursday.
The collapse buried 22 people, most of them construction workers and those staying in the ground floor stores.
The renovation project entailed adding one more floor on the originally four-story building. The addition put excessive weight on the building, and was the direct cause of the collapse, according to experts.
Experts found the strength of building's walls failed to measure up to the standard, which also contributed to the accident.
Moreover, incorrect renovation methods, such as removing the wood windows, also weakened the strength of the building walls.
The causes of the collapse will be investigated thoroughly and those held responsible will be punished, said Jiang Shaocai, head of the Provincial Administration of Work Safety.