Click in the Eyewitness News story window above to watch Amy Powell's report from El Monte.
But the investigation isn't over. Police say these suspects were operating out of several locations.
The upstairs bedrooms of the El Monte home looked more like a greenhouse. They were filled with nearly 1,000 marijuana plants in various stages of growth.
Detectives had been keeping the house in the gated community of Maxson Villas in the 2800 block of North Maxson Road under surveillance after being tipped about the operation a month ago.
Around 10 p.m. Thursday, authorities stopped two men who were renting the house.
"And last night they stopped a vehicle that was leaving with some marijuana in it. They came back to the house and located over a million dollars worth of plants," said Sgt. David Vautrin, El Monte Police Department.
Twenty-two-year-old Henry Kwong, a Pasadena City College student, and 25-year-old Yue Huan Mai were arrested.
The two men were allegedly stealing electricity to provide lights for their plants and power the operation's air system. Police say the marijuana-growing setup was extensive.
"It's a very sophisticated cultivation system with lighting, a ventilation system, and a self-contained watering system within the residence," said Sgt. Vautrin.
Neighbors say they didn't notice anything suspicious.
"No, I never, I never heard anything," said neighbor Sam Dodwin. "The owner of the house rented it several times to other people."
During the night investigators went to another residence in the City of Walnut, where they found more equipment for cultivating marijuana. They believe the suspects were just starting to set up an operation there.
At a third home in San Gabriel, authorities found about a kilo of packaged pot and several thousand dollars in cash. A third suspect, 32-year-old Denise Quan, was taken into custody at the San Gabriel home.
Police also took a $50,000 BMW from the home in El Monte.
All three suspects are from the San Gabriel area. They're facing felony charges and are due in court on Monday.