Two people were stabbed at a Tufts University fraternity house early Sunday, leading the school to briefly issue a shelter-in-place order as police searched the campus for a suspect or suspects.

The victims, who are not affiliated with the university, were sent to the hospital, where the severity of their injuries was unknown.

The stabbing occurred at the Delta Tau Delta fraternity house on Professors Row, a street that runs through the Boston-area campus, Tufts spokeswoman Kim Thurler said.

School officials had asked students through social media and email alerts to seek shelter and to lock their doors at about 5 a.m. while police responded to reports of a "serious crime." The shelter-in-place advisory was lifted at about 8 a.m.

Somerville police spokesman Lt. Joseph McCain said there were no suspects in custody and investigators were still interviewing witnesses.

Tufts' commencement was held on May 17 and summer sessions are underway. However, Thurler said, the stabbing victims are not affiliated with the university.

Even though students may return to their normal activities, there will continue to be an enhanced police presence on campus as the investigation continues, Thurler said.