BELLINGHAM, Wash. (AP) — Western Washington University in Bellingham has reported 30 positive COVID-19 cases involving students living in residence halls in the past week.

According to a school alert sent out Monday, Western’s Student Health Center and the Whatcom County Health Department have tied the sharp increase in new cases to the residence areas, The Bellingham Herald reported.

Officials said further contact tracing will be needed to determine the cause for these increases.

The outbreak was initially thought to be tied to off-campus parties and other large social gatherings.

“Remember that wearing a face mask, washing your hands frequently, practicing physical distancing, and gathering with no more than (five) people outside of your household, preferably outdoors, remain the best ways to protect against COVID-19,” the alert said.

According to the school’s COVID dashboard, Western Washington had 49 COVID-positive results in 13,291 tests run (0.37%) That is up from the 38 positive results in 13,749 tests (0.28%) during the fall quarter. The spring quarter beings Tuesday.