A sorority in Ewing hosted a party last week, and at least 19 people who attended the party then tested positive for COVID-19, officials said.

Ewing Mayor Bert Steinmann did not disclose the name of the sorority but said on Thursday evening that the party happened at a home that was being rented to members of the sorority near the intersection of Upper Ferry Road and Lower Road.

“Now we’re doing the tracing to see who they were in contact with, The health department and the county have been working through the issues of notifying people,” Steinmann said.

On Monday, Ewing Business Administrator Jim McManimon said another nine students tested positive since Thursday. It was unclear whether they were all party attendees. Asked to clarify, McManimon did not confirm that they were all attendees at that particular party. He said he did not know the name of the sorority that hosted the party.

He said at least 205 off-campus students living in Ewing have been tested for COVID-19 since the party. He said the students tested had possible contact with people from the party who had tested positive for COVID-19. “Some of them attended multiple parties,” McManimon said in an email on Monday.

McManimon said he would be receiving an update on Tuesday after the holiday weekend and would have more information then.

Ewing is home to the College of New Jersey and Rider University is nearby in Lawrence. The College of New Jersey has more than 30 fraternities and sororities. Rider has more than 15 fraternities and sororities, and more than 14 percent of students at the university are involved in a fraternity or sorority.

Many area schools, including the College of New Jersey and Princeton University, are conducting classes remotely for the fall semester. But many undergraduate students are renting houses in groups in and near the college towns so they can still spend the semester with their friends from school. The student rentals have raised concerns among area residents, who worry about student parties and the potential spread of the virus.