There is growing concern about a reported outbreak of coronavirus cases at a popular South Bay Costco store.

The Santa Clara County Health Department confirmed it is investigating cases among multiple employees at the Costco on Lawrence Station Road in Sunnyvale.

The number of cases went up on Wednesday and it has many workers and customers worried.

Word about the coronavirus cases at the Sunnyvale Costco has been spreading online for a while now. But some people tell NBC Bay Area the public deserves more than just a "word of mouth" warning.

The company has posted a new note on its employee bulletin board at the Sunnyvale location, which said the number of COVID-19 cases among workers is now up to nine employees.