The University of Pennsylvania on Thursday banned indoor social gatherings for the rest of the semester due to a growing number of coronavirus cases on campus.

In a message to the community, interim provost Beth Winkelstein, senior executive vice president Craig Carnaroli, and associate provost and chief wellness office Benoit Dubé said that during the last week of testing, the university had recorded 133 COVID-19 cases in the span of three days, compared with 120 the prior week.

The new cases are primarily among students and linked to indoor social gatherings, the officials said. They also pointed to rising positivity rates in Philadelphia (7%) and Montgomery County (9.7%).

“As we head into the final weeks of the semester, it is our collective responsibility to mitigate further widespread positivity that would prevent students from completing their academic requirements and traveling home for the holidays,” the officials said. Friday marks the last day of classes, while the semester ends Dec. 22. Classes for the spring term begin Jan. 12.

Penn began informing student groups Wednesday that social events must be canceled, according to the Daily Pennsylvanian, the student newspaper. The university had previously recommended that students limit social gatherings and that faculty and staff postpone December gatherings until January.

Earlier this semester, the university, which enrolls 28,000 full- and part-time students, moved to prevent students from registering early for spring classes and to block access to buildings if they had not complied with COVID-19 vaccination and testing requirements. At the time, officials said about 99% of undergraduates were vaccinated, but vaccinated students and staff are still required to participate in screening testing.

Penn still has not documented any cases of classroom or workplace transmission of the virus, officials said. But they said the ban on indoor social gatherings was out of “an abundance of caution.”