Seventeen students at St. Olaf College in Northfield have been suspended for the fall semester after attending an off-campus party where masks were not worn and at least one student present was already infected with COVID-19, the school announced Thursday.

“This is the kind of reckless behavior that will put an end to our in-person semester, and it must stop,” St. Olaf President David Anderson said.

Fifty students need to quarantine due to a lack of social distancing. Much of the quarantine is needed because of the off-campus party, which was held last week before students moved into campus housing, Anderson said.

School officials learned that people congregated at the party and did not practice social distancing. “The predictable results ensued,” Anderson said.

Several students were exposed to COVID-19 at the party by another who was infected. Others in attendance “exposed innocent students” such as their roommates, Anderson said.

The incident occurred as colleges and universities statewide try to prepare for fall classes with varying degrees of restrictions and distancing.

Students will need to hold one another accountable for such behavior to complete the full semester in person, Anderson said.

He urged them to wear masks, socially distance, monitor symptoms and honor a public health pledge they signed before arriving on campus.

“It is now up to all of us to act safely and to look out for each other’s health,” Anderson said.

School officials also announced they administered more than 3,400 COVID-19 tests to students, faculty and staff as they reopened campus. Results from 3,055 tests have come back with a 0.3% positive rate.

As of Thursday morning, the college had eight students who have tested positive.

All St. Olaf students will be tested again in two weeks, with random testing throughout the semester.

Students are also expected to complete daily health screenings before attending in-person classes.