All of them were rushed to Ram Manohar Lohia hospital and are undergoing treatment.
"The staff had lunch at the staff canteen at 2.30 p.m. after which they complained of uneasiness," a police officer said.
According to hospital authorities, the patients are not serious and are likely to be discharged after primary treatment.
Authorities said that at the initial stage, it was difficult to ascertain what had caused the food poisoning.
"A case under section 337 (Causing hurt by act endangering life or personal safety of others) of Indian Penal Code has been registered and we are investigating into the matter," Additional Commissioner of Police K.C. Dwivedi said.