Police have now shut down Nassau Street along the front of the campus.
Princeton University is now on spring break and classes are not in session.
Message goes out to Princeton University community saying the message about sheltering in place and shots being fired was a mistake.
"Municipality of Princeton police continue to surround an armed man inside the Panera restaurant on Nassau Street, across from campus". Police on the scene said the man is held up inside the eatery. Police had been negotiating with the man earlier, in a standoff that began at around 10:30 Tuesday morning.More news: One trophy not good enough for Manchester United, says Nemanja Matic
According to the Princeton University alert page, two campus buildings near the restaurant have been evacuated as a precaution.
As this story is developing, more information will be updated as made available.
Authorities said there are "no known hostages" and no one has been hurt. Peter Aseltine, a spokesman for the office, said that police "fatally shot a man who entered a restaurant with a gun, leading to a lengthy standoff with officers".