How do i report health code violations?

I worked for a restaurant that among other violations: did not supply clean aprons or hairnets, had enormous cockroaches (3 inches long at least), ant infestations that the manager continues to ignore, food that is left uncontained and unrefridgerated for up to 8 hours at a time and allows one employee to provide his own knives and utensils from home to prepare food. How do I report them before someone gets sick?