DURHAM, N.H. (AP) — The president of the University of New Hampshire says 11 cases of the virus that causes COVID-19 have been traced to a fraternity party.

In a Sunday letter to the university community, UNH President James Dean said more than 100 students and non-students attended the Aug. 29 party at the Theta Chi fraternity. Dean called the party “reckless behavior” that could force the Durham school to switch to a fully remote learning mode. He called the party reprehensible.

Student conduct charges will be pursued against the organizers of the party and all students who attended the event. Dean ordered a moratorium on any in-person gatherings of any size within the fraternity, or sorority system or other social groups.