LOOMIS -- A fourth person has died from eating a soup made with poisonous mushrooms earlier this month at senior care facility in Northern California, authorities said Tuesday.
The Placer County Sheriff's Department identified the woman as Dorothy Mary Hart, 92.
Three others at the six-bed Gold Age Villa care facility in Loomis died from eating the mushrooms in what sheriff's investigators characterize as an accident.
"This is an ongoing tragedy, an unfortunate accident," said Dena Erwin, spokeswoman for the sheriff's office.
All of the victims were sickened Nov. 8, including the caretaker who made the soup after picking mushrooms in the backyard of the facility.
The other people who have died were identified as Barbara Lopes, 86; Teresa Olesniewicz, 73; and Frank Warren Blodgett, 90.
California's Department of Social Services is investigating the incident, though sheriff's investigators have said the caretaker who made the soup did not know that the mushrooms were poisonous.
The most recent death occurred at a nursing home, where the victim was transferred from a Sacramento-area hospital.
Vomiting and diarrhea associated with mushroom poisoning can take 12 hours or longer to develop, which often makes it difficult to diagnose, said Dr. Kent R. Olson, medical director of the San Francisco division of the California Poison Control System.
The loss of fluids can cause kidney failure, but the poisons attack the liver and stop the organ from producing normal proteins. The victim usually falls into a coma, and the liver eventually shuts down and dies.
Fall begins the season for highly sought-after wild chanterelle mushrooms in Northern California, and for the amanita species of mushroom that include what are known as "death cap" and "death angel" varieties.
Mushroom experts said that young poisonous North American amanitas found in the San Francisco Bay Area can often look like an edible version of a wild mushroom popular in Asia.
California recorded 1,700 cases of mushroom-related illnesses from 2009 to 2010, including two deaths.