AGUANGA, Calif. - Detectives are investigating what prompted the Labor Day killings of seven people at an illegal marijuana growing operation in a rural Southern California community known for horse ranches and plant nurseries along dirt roads.

Authorities said Tuesday that the shootings in a small community north of San Diego appeared to be isolated and don't represent a threat to the general public.

Deputies who arrived at a house before dawn Monday found a woman suffering from gunshot wounds who later died and the bodies of six more people.

The killings are the latest flashpoint in the violence that often permeates California's illegal marijuana market.