A public health official on Monday said that almost 200 people who recently ate at a catered party at a downtown Seattle office building have been reported to be infected with norovirus.

Dr. Meagan Kay, a medical epidemiologist for the public health department, said in a statement that public health officials closed all the food-service locations inside the Russell Investments Center in downtown Seattle. A Starbucks location was also order to be closed.

According to the US Centers for Disease Control and Prevention (CDC), norovirus can spread by an infected person, contaminated food, water or infected surface.

Kay said in a statement that of 600 people who attended the party catered by California-based Bon Appetit Management Co on Tuesday, 200 reported that they were sick.

“The source illness remains unclear, and we are eager to learn how and when it began. We have worked with our food safety experts to disinfect surfaces in our facility and have taken all other necessary steps to ensure food safety”, the catering company said.

Of 200 reported cases, two were hospitalized overnight and eight people visited an emergency room for the illness. Kay said the present condition of those patients is unknown to them.

The entire building was disinfected overnight in part to address vomiting in restrooms and to clean door knobs and other surfaces, Kay said.

According to CDC, the virus causes inflammation of stomach or intestine or both with acute gastroenteritis which leads to stomach pain, nausea and diarrhea.