One man is facing charges after Toronto police seized nearly 14,000 marijuana plants -- the biggest such drug bust in at least five years, according to a senior officer.

"It was unbelievable in terms of size and scope," Insp. Mario Di Tommaso of the Toronto police drug squad told reporters at the scene on Wednesday.

Officers from the drug squad carried out the raid at an industrial building located at 120 Cartwright Ave., which is about half a kilometre west of the Yorkdale Shopping Centre.

"What we found was quite astonishing. We found a two-level marijuana production factory," Di Tommaso said.

"During the execution of the warrant, a very large and sophisticated soil-based marijuana grow operation was located in a segregated two-storey area of the building," police alleged in a news release issued Wednesday.

"The operation included the use of conveyer belts to ease the transport of potted plants from one stage of growth to the next, and a professionally installed commercial-grade hydro bypass directly to an exterior transformer."

Besides the plants, police said they seized an unspecified quantity of dried marijuana along with 13,730 plants.

They estimate the street value of the marijuana to be $13.7 million.

Di Tommaso said the man they have in custody has been charged with producing marijuana and possession of marijuana for the purpose of trafficking.

People with information are asked to contact police at 416-808-6100, Crime Stoppers anonymously at 416-222-TIPS (8477), online at, text TOR and a message to CRIMES (274637).

Grow-op fire

On Wednesday morning, Toronto firefighters responded to a blaze on St. Clair Ave. W. near Runnymede Road.

After extinguishing the blaze, they found a marijuana grow-op that consisted of hundreds of plants.

A rottweiler, believed to be used as a guard dog for the operation, was taken from the scene.

Hydro to the building had been bypassed to power the grow-op, fire officials said.

Police were to get a search warrant and remove the plants Wednesday afternoon.