Around 4 p.m. Friday, Upland police headed to a warehouse in the city over a call about suspicious activity regarding narcotics.
When officers arrived, they conducted an investigation and believed a grow operation was likely. With help from the Ontario Upland Narcotics Task Force, authorities were able to seize more than 16,000 marijuana plants.
Authorities said the seizure suggested an illegal for-profit operation that sold pot on the streets and in dispensaries.