TRENTON (CBSNewYork) – The New Jersey Health Department is looking into eight cases of E. coli in four counties.

As CBS2’s Meg Baker reported, there are few details about where the patients may have been infected.

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So far, eight people have been hospitalized by the E. coli outbreak, but state health officials can’t yet say how the cases are connected – only that there is a possible association with a chain restaurant.

The health department said it can be very difficult to determine where someone got sick.

“Individuals could have eaten a number of meals in a number of places before getting sick. They could have eaten at several restaurants, at home or eaten food purchased at a supermarket. Sometimes the source of the food that made people sick is never determined,” officials said in a statement.

Dr. Raj Kapila, a professor in the department of medicine at Rutgers University, explained E. coli is a form of food poisoning that can be extremely dangerous. Symptoms include fever, vomiting, and diarrhea.

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He said if you see those signs, you should go to the hospital immediately.

The health department said it is in the early stages of an investigation that involves pending lab tests and interviewing patients who became ill.

“They are like detectives. These detectives who are called epidemiologists will go and start investigating, they will look at all patients,” said Kapila. “They will take a detailed questionnaire, saying, ‘What did they do? What did they eat? Where did they go? Even, did they wash their hands?'”

Five of the eight patients have been discharged from the hospital.

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The health department also said the outbreak may be broader than a single chain restaurant.