One woman had died and more than 20 are sick after eating a mushroom dish at a Michelin-starred restaurant in Spain.
On Saturday (local time), 46-year-old Maria Jesus Fernandez Calvo was celebrating her husband's birthday with their 10-year-old son at Valencia's RiFF restaurant.
But the night out turned deadly when she ordered a rice and morchella fungi dish which led her to vomit and have diarrhoea the following morning before dying.
The mushrooms are believed to contain the toxin hydrazine, meaning they cannot be eaten raw and must be hydrated before being cooked.
Samples of the mushrooms have been sent to the country's National Toxicology Institute for testing, while an autopsy is underway to reveal if the woman died from poisoning or asphyxiation from suffocating on vomit.
Between 11 and 23 patrons are reported to have also fallen ill with mild symptoms, including Ms Calvo's husband and son.
Despite health officials not finding anything which may have contributed to food poisoning in the restaurant, its chef closed the establishment until the investigation into the mushrooms has been completed.
"Regardless of the reason that may have caused this situation, I want to convey my deep regret for what happened, hoping that soon all these facts can be clarified," chef Bernd Knoller said.
Mr Knoller has since cancelled appearances at the Valencia Culinary Festival.