The state attorney general's office tells Action News that the suspect's death was possibly the result of a police-involved shooting.
Henry House and Scheide-Caldwell, the two campus buildings closest to the restaurant, were evacuated.
Police have surrounded a Panera Bread near the Princeton University camps after a gunman was reported to be inside.
Princeton police alerted residents in the area to stay away and traffic was closed between Washington and Witherspoon streets.
Police say there were "no known hostages" in the Panera Bread, and it's unclear what sparked the standoff that began around 10am Tuesday.
Princeton Schools are having students shelter in place, but Sutter said the situation has been contained.
Authorities had shut down Princeton's downtown area and two buildings on the university's campus were evacuated as a precaution.
The eatery is located across the street from the university.
Princeton University is now on lockdown, per reports.
Classes are not in session as it was the university's spring break.
It's unknown whether the gunman has any connection to the school. "'Shelter-in-place' keeps us secure indoors, instruction able to continue and on stand-by for updates".