DURHAM, N.C. (AP) — Duke University issued a quarantine order for all of its undergraduates effective Saturday night due to a coronavirus outbreak caused by students who attended recruitment parties, the school said.

The university said in a statement that all undergraduate students will be forced to stay-in-place until at least March 21. Suspension or dismissal from the school are potential punishments for “flagrant or repeat violators.”

Over the past week, the school has reported more than 180 positive coronavirus cases among students. There are an additional 200 students who may have been exposed and have been ordered to quarantine.

The school said in the statement that the outbreak was “principally driven by students attending recruitment parties for selective living groups.”

Duke said it would provide a policy update on Thursday.