Four people, including three Chinese engineers, were killed when the shuttering at the construction site for the Tarbela extension project in Haripur collapsed on Sunday.
The shuttering collapsed during construction work on the project, Station House Officer Topi Sultan Mehmood Khan said, adding that four other people, including two Chinese nationals, were injured during the incident.
Rescue sources said the Chinese engineers and labourers were engaged in routine development work when the shuttering suddenly came down burying the people present at the scene under the debris.
Bodies of the victims were pulled out from under the rubble and shifted to a hospital.
Rescue personnel were searching the debris as more people were feared to be buried under the rubble.
Prime Minister Nawaz Sharif meanwhile conveyed his condolences to the families of the Chinese engineers who lost their lives during the expansion work on the dam.
In a statement issued on Sunday, the premier directed the authorities concerned to make quick arrangements for sending the bodies of the deceased engineers to their home country and to ensure the well-being and safety of Chinese engineers working on the project.