DURHAM, N.C. (AP) — Duke University has lifted a stay-in-place order it issued last week for all undergraduate students following a spike in COVID-19 cases that officials blamed largely on students attending fraternity rush events.

The lifting of the order Sunday morning means all in-person courses will resume their standard delivery method, whether in-person or hybrid.

Students living in university-provided housing are again allowed to move about campus, but are being asked to leave campus only for essential travel and health-related activities through March 28.

Students living off-campus in the Durham area are permitted to be on campus only to attend in-person classes and essential academic activities, participate in surveillance testing, seek medical care or pick up food orders.

Libraries will reopen for undergraduates, but indoor dining on campus is not allowed. Indoor gatherings are limited to 10 people, on or off-campus, unless permission for a larger student event is granted.

The stay-in-place order was imposed March 13 after a week in which more than 180 students were in isolation after testing positive, and another 200 students were in quarantine as a result of contact tracing.

Officials said last week that more than 550 students had contracted the virus since Jan. 3, compared to a total of 241 cases reported during the entire fall semester.

Michael Schoenfeld, vice president for public affairs and government relations at Duke, said most of cases that prompted the lockdown came from recruitment parties held off campus by “unsanctioned fraternities.”

Amid changes to the rush process and other restrictions because of the coronavirus, nine fraternities decided to sever ties with the university and form a group called the Durham Interfraternity Council, which has more than 700 members. In a statement, the council said it supported Duke’s shelter-in-place directive and expressed disappointment that some individuals had violated expectations for virtual recruitment.