Health departments in New Jersey are in the early stages of an investigation into eight cases of E. coli in four counties, and NJ.com is reporting that Panera Bread is part of the search. Eight people were hospitalized and five discharged as of Saturday (April 7).

NJ.com reported that Panera Bread, and specifically a Phillipsburg location, are being looked at, although the chain has not been definitively determined to be the source. Sarah Perramant, public health epidemiologist in Warren County, told the media outlet that several E. coli cases potentially could have stemmed from “local Panera breads.” State health officials posted a statement over the weekend and did not name Panera specifically, saying: “The department is investigating a possible association with a chain restaurant, but the association may be broader than a single chain restaurant. The department is in the process of gathering food history data from those who became ill,” according to the statement from the New Jersey Department of Health.”

The four counties under investigation are Somerset, Hunterdon, Middlesex, and Warren. State and local health officials are working with the U.S. Food and Drug Administration and the Centers for Disease Control and Prevention on the investigation. In a statement, reported by CNBC, the Department said it is conducting interviews to get “food history data.”

“It can be very difficult to determine where someone got sick,” the department said in a statement. “Individuals could have eaten a number of meals in a number of places before becoming ill. They could have eaten at several restaurants, at home or eaten food purchased at a supermarket. Sometimes the food source associated with illness is never determined,” the statement said.

The Department is conducting lab tests to determine if the strain of E. coli bacteria match among the affected parties. The federal Centers for Disease Control and Prevention will then conduct confirmatory tests.

Perramant also told NJ.com that most of the New Jersey cases date back to the third week of March.

“We’re working with the FDA district office in New Jersey and our own investigators to trace back sources of food the individuals may have eaten as well as looking at records such as invoices of vouchers of food deliveries made to any of the restaurants that may be part of the investigation,” the health department’s statement continued.