Health officials are investigating a possible norovirus outbreak after dozens of people fell ill after eating raw oysters at the LA Times’ 101 Best Restaurants event.

The Los Angeles County Department of Public Health confirmed that more than 80 people who attended the annual event – which features some of the area’s most famous and popular restaurants – reported becoming ill with symptoms including diarrhea, nausea, abdominal pain and vomiting be.

According to a Department of Health spokesperson, the illnesses appear to be linked to the raw oysters provided at the Dec. 3 event, which have since been recalled.

The dozens of illnesses reported from the event occurred just days before the California Department of Public Health issued a warning on Dec. 13 not to eat raw British Columbia oysters. The U.S. Food and Drug Administration has since warned restaurants and retailers not to sell the oysters because of possible norovirus contamination. The warning affected restaurants and retailers in several states, and the company that supplied the oysters issued an urgent recall and warned consumers not to eat them.

According to Hillary Manning, a spokeswoman for the Los Angeles Times, the oysters were supplied by Fanny Bay Oysters. The oysters were procured by Santa Monica Seafood, a sponsor of the event, and delivered to one of the restaurants listed on the 101 Best Restaurants list, Manning said.

News of the possible outbreak was first reported by LA Taco.

As with previous Los Angeles Times events, Manning said all safety protocols were followed at the event.

“We have been organizing culinary events for many years and take food safety very seriously,” she wrote in an email. “As with all of our events, we had protocols in place and adhered to all relevant safety standards based on an inspection by the LA County Department of Public Health. We also know how much care each chef and restaurant takes in preparing and serving food to our community.”

Without specific testing, there is no way for a vendor or restaurant to detect norovirus because it does not affect the taste, smell, or appearance of oysters.

The Los Angeles Times first became aware on December 11 that some people at the event became ill. Company officials, who did not know the cause, referred the people to the LA County Department of Health. On Dec. 12, the health department contacted the Times about a group of people who had reported being sick.

There were people who attended the event who reported that they did not see any notices or warnings from the Los Angeles County Department of Public Health.

Jamie Clegg, who bought two tickets for the event, said he never saw a reference in his email.

“I didn’t get anything unless it accidentally ended up in spam,” he said.

He went to the event with a friend who works at the LA Times, he said, and that person received an email from county health officials informing them of the disease’s prevalence and asking them to have one to answer anonymous questionnaires.

The oysters served Dec. 3 were among a batch of recalled Fanny Bay Select and Fanny Bay XS oysters from Pacific Northwest Shellfish Co. that were packaged Nov. 25, the county health department spokesman said.

The outbreak is still under investigation.

According to the FDA, someone infected with the virus could experience symptoms for 12 to 48 hours.