The School District of Philadelphia said Thursday that at least 63 schools under its jurisdiction would remain closed Friday due to staff shortage.

Pennsylvania Governor Tom Wolf earlier on Thursday ordered mass closure across Montgomery County. He advised the residents to avoid nonessential travel and going to work after the region reported the most number of COVID-19 cases in the state. The school district officials said over 15% of the staff at the 63 schools and 2,100 (11%) of its overall 18,000 employees were from the region. The school district said the staff shortage at the schools has impeded their effective operation.

“Since the onset of the coronavirus situation in the Philadelphia area, it has been the goal of our School District to safely keep our doors open as long as possible,” William Hite, Superintendent of SDP, said in a press release. “The Philadelphia communities we serve rely on us for the many public school services we provide, including breakfast and lunch meals, shelter and health services. Unfortunately, the current set of circumstances make it difficult for us to keep all of our schools open.”

Pennsylvania reported 22 total cases as of Friday, with Montgomery County accounting for 13.

Students sit in class at Sidney High School
Students sit in class at Sidney High School AFP / Megan JELINGER