New Jersey and four of its counties are investigating a cluster of E. coli illnesses that might be linked to a Panera Bread restaurant in Phillipsburg, NJ.

Local media reported the investigation earlier this week, with initial details implicating three counties and what public health officials described as a “chain restaurant.” Officials declined to discuss the chain or specific locations at that time.

That vagueness turned to cautious specificity Thursday when Sarah Perramant, public health epidemiologist in Warren County, told NJ.com that the E. coli infections are potentially from local Panera Bread locations. She told NJ.com the Phillipsburg location was the primary target of the outbreak investigation. 

The other three counties involved, confirmed Thursday by the New Jersey Health Department, are Hunterdon, Middlesex and Somerset. 

A specific source for the E. coli has not been determined and the outbreak remains under investigation.  

Panera’s corporate office is in Sunset Hills, MO. It operates more than 2,000 restaurant-bakeries and has more than $5 billion in annual sales, according to the Panera website.