AGUANGA, Calif. — Detectives on Tuesday investigated what prompted the Labor Day killings of seven people at an illegal marijuana growing operation in a small, rural Southern California community known for its horse ranches and nurseries along dirt roads.

The fatal shootings in Aguanga, north of San Diego, represent the latest flashpoint in the violence that often permeates California’s illegal marijuana market.

The state broadly legalized recreational marijuana sales in January 2018 but the illicit market is thriving — in part because hefty legal marijuana taxes send consumers looking for better deals in the illegal economy.

Before dawn Monday, Riverside County sheriff’s deputies responded to a report of an assault with a deadly weapon at an Aguanga home. They found a woman suffering from gunshot wounds who later died at a hospital, according to a sheriff’s department statement.

The deputies also discovered six more dead people at the house that “was being used to manufacture and harvest an illicit marijuana operation,” the statement said.

Investigators seized more than 1,000 pounds of marijuana and several hundred marijuana plants.

While officials said they did not immediately find any suspects, the sheriff’s statement called the deaths “an isolated incident” that did not threaten people in Aguanga, population about 2,000.

“The area is safe and we don’t have any other concerns,” sheriff’s Sgt. Deanna Pecoraro said.

Partially eaten pizza sat in boxes on the ground in a circular dirt driveway of the dilapidated two-bedroom house where the shootings occurred. Three cars with California or Nevada license plates were parked outside, including a Toyota Sequoia with its front doors open.

Cases of bottled water were stacked on the front porch, and clothing and plastic bags were strewn about. A black tarp was stretched atop poles in the fenced backyard, indicating a small growing operation.

A wooden sign with the property’s address at the foot of a long driveway had a strand of yellow police tape tied to it. Unlike many neighboring homes, it had no gate at the entrance or trespassing signs.

The sheriff’s department declined to give additional details about the case, but officials planned to hold a news conference in the afternoon.

Aguanga is in the Temecula Valley, dotted with vineyards and horse ranches that have given it some traction as a weekend getaway for Southern California residents. It’s near the small city of Temecula, a bedroom community for San Diego and Los Angeles.

Aguanga itself is a one-stop-sign place with a post office, a general store and a real estate brokerage. Its few commercial establishments give way to horse ranches and nurseries along dirt roads, many behind gates and “no trespassing” signs.

Sheriff’s deputies in February seized more than 9,900 plants and collected 411 pounds (186 kilograms) of processed marijuana and firearms from suspected illegal marijuana sites in the Aguanga area. Four people were arrested.

The law enforcement seizures of the area’s illegal growing operations have spawned nicknames for the raids like “Marijuana Mondays,” “Weed Wednesdays” and “THC Thursdays,” according to Mike Reed, a real estate broker and 28-year Aguanga resident.

Reed said he does business with pot growers who operate legally and illegally – some of whom live in his gated community.

Residents move to Aguanga for “peace and solitude,” plus good camping, Reed said.

“People live here because it’s not in the city,” Reed said.

Aguanga’s isolation, however, may have helped make it prone to illegal marijuana sales and cultivation.

Adam Spiker, executive director of the Southern California Coalition, a cannabis industry group, said the shootings were a reminder that the sprawling illegal marketplace remains largely unchecked.

“Shame on all of us: It seems we have one foot in and one foot out on regulating this industry,” Spiker said.

Many California communities have not established legal marijuana markets or have banned commercial marijuana activity. Law enforcement has been unable to keep up with the illicit growing operations.

“This risk is inherent in the underground market,” said Los Angeles marijuana dispensary owner Jerred Kiloh, who heads United Cannabis Business Association, an industry group. “When you have money and high returns, people want to take that from you.”

Kiloh said most illicit market crimes go unreported because illegal marijuana farmers who have been robbed cannot turn to authorities.

Large cannabis growing operations typically have hundreds of thousands of dollars of product at each site, making them attractive targets for criminals.

“That’s why the violence becomes worse and worse,” Kiloh said.

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