The mill is located in the community of Lavington and is owned by Tolko Industries.
Rob Fraser, general manager at Tolko's Southern Interior division, said the accident happened around 2 a.m. PT on Saturday.
"An employee became entangled in a piece of equipment, a conveyor, and subsequently died as a result of his injuries," Fraser said.
The teen's identity has not been released, but the company said he had not yet graduated from high school.
WorksafeBC and the Coroner's officer are now investigating. Tolko says it is also doing its own internal review and will provide counselling for its workers.
Work at the mill has stopped until WorksafeBC indicates operations can continue.