The Los Angeles Police Department discovered an estimated $1 million in marijuana at a downtown commercial building that caught fire today.

Firefighters knocked down the structure fire that engulfed a one-story commercial building, but inside they found 1,000 pot plants as well as what appeared to be a plant-growing operation.

Several Los Angeles Fire Department trucks were called to the scene in the 600 block of South Santa Fe Avenue at 6:40 a.m., department spokesman Erik Scott said. It took 75 firefighters nearly 40 minutes to extinguish the blaze, Scott said. No injuries were reported.

-- Raja Abdulrahim

Photo: Los Angeles city firefighters extinguish an early-morning fire in an industrial building in downtown L.A. Credit: Mark Boster / Los Angeles Times >>More photos