Police in Chicago found more than they bargained for when they discovered a giant marijuana farm.

On Tuesday, a police helicopter was on a routine patrol flight when it flew over a field in Southeast Side and looked down to see a marijuana farm reportedly the size of two football fields, according to the Chicago Tribune.

"I told (my partner), 'Turn around, let's go check this out, make sure we have what we have here,'" said Ed Graney, one of two officers from the Cook County sheriff's office that spotted the farm.

The field contained 1,500 6-foot tall marijuana plants as well as camping equipment with food.

Nick Roti, chief of the Police Department's bureau of organized crime, complimented the officers' work in a news conference saying, "If it wasn't for the helicopter unit, we would have never found it."

On Wednesday, Graney and pilot Stanley Kuprianczyk were credited with finding the largest outdoor marijuana operation in recent Chicago history, according to the police.  

The estimated value of the total crop is around $10 million, as reported by the Cincinnati Times.

Chicago's climate isn't conducive to having an outdoor marijuana operation which made police surprised by the 6 foot height of plants.

"Usually you see marijuana plants that are 3 feet high, 4 feet high, (but) these resemble plants you see out in California," Roti said.

The farm is located in an industrial area and was blocked by tall grass so it wasn't able to be identified until now.

"We just happened to be right over a small hole in the trees and we looked down," Officer Kuprianczyk said.

No one has been arrested as of yet, but a suspect was seen running near the farm when the helicopter arrived, police said. The plants will be burned and a chemical will be used to make sure marijuana can't be grown in the field again.