The incident occurred on Saturday afternoon. Dozens of workers were mining marble when a heavy rock tumbled down, trapping the workers underneath.
The stone slide also destroyed dozens of vehicles, including trucks, excavators, tractors and other heavy machinery, at the site.
"The slide happened after a blast to break the mountain and the labourers had started the excavation work," a witness told The Express Tribune.
Doctor confirmed that among the five injured, four were in a critical condition while one received minor injuries. The four critically injured were referred to a hospital in Peshawar.
The local administration has imposed an emergency in the mining area and the sites would remain closed until further orders.
"The operation to recover the trapped people is under way," an administration official said.
Buner is among the biggest marble producers in the country. Manual mining in the mountainous areas often leads to tragedies in the district; however, because of the low scale, such incidents are not reported by the media.