San Francisco area news reports that Hotel Sofitel in Redwood City closed its kitchen and dining facilities last week after dozens of guests and a few employees reported becoming ill at the annual NAACP State Convention, including former Oakland Mayor Elihu Harris.

San Mateo County public health officials, with help from the California Department of Public Health, are investigating what could be an outbreak of foodborne illness during the Oct. 23 to Oct. 26 event. The cause of the sicknesses has not been confirmed, but officials hope lab tests this week will provide clarity.

A hotel spokeswoman said food and beverage service was suspended “out of an abundance of caution we responded as if either cause was possible — foodborne illness or community acquired virus such as norovirus.”

On the morning of Oct. 26, 12 convention attendees were taken by ambulance to a local hospital — and several others drove themselves — after complaining of gastrointestinal symptoms including nausea, vomiting and diarrhea, officials said. More people who were at the event have since reported problems.

“One hundred-plus of my members have either been in the hospital or ill because of food poisoning,” said Alice Huffman, president of the California NAACP. “ I’ve never seen anything like this at a hotel.”