GUILDERLAND — The Guilderland Central School District has announced three new cases of COVID-19 — two at Guilderland High School and one at Lynnwood Elementary School.

This makes a total of 13 confirmed cases for the district so far this school year.

The school district learned of the new cases on Thursday and Friday, according to an email Superintendent Marie Wiles sent to school district families on Friday evening.

The high school moved to all-remote learning on Thursday, Nov. 19, which will last until Thanksgiving break, which starts on Tuesday, Nov. 24. The in-person classes were canceled because so many staff members were quarantined, Wiles wrote in an email on Wednesday, announcing another case at the school.

The high school had previously been on a hybrid schedule with some in-person classes and some remote classes.

Albany County has been experiencing a surge in COVID-19 cases in recent weeks, as has the rest of the country, since schools opened in the fall and people have returned to more inside activities.

Last week, Albany County’s health commissioner, Elizabeth Whalen, said that about 15 percent of the county’s COVID-19 cases in the last two months had come from students in kindergarten through 12th grade.

Whalen urged parents to keep their children home when they are sick and to get them tested. At a press conference on Nov. 13, Whalen urged parents to be sure their children wear masks and not attend parties.

This week, Albany County launched two testing sites — one of them in Voorheesville — where students with symptoms like coughing and running a fever, who are therefore excluded from classes, can get tested for COVID-19. Appointments are coordinated through school nurses.

The state’s COVID-19 Report Card, as of Friday evening, had not yet listed the three new Guilderland cases. It reported, of the earlier 10 cases, two students at Altamont Elementary School — those cases were in September — as well as two cases at Farnsworth Middle School of one student and one teacher, and six cases at the high school of five students and one staff member.

In addition to its middle school and high school, Guilderland has five elementary schools. No cases have yet been reported at Westmere, Pine Bush, or Guilderland elementary schools.

Last March, a woman in her 30s associated with Farnsworth Middle School had one of the first two cases of COVID-19 announced in Albany County. Shortly thereafter, the governor shut down all schools across New York for in-person learning.

Guilderland, like other school districts, went to remote learning. Then, for this school year, the district developed plans that allow younger students to learn in person while older students combine remote learning with in-person learning. Some students have chosen to learn entirely from home.