Lyseth Elementary School in Portland will reopen Tuesday after being closed for a day because of a nine-case COVID-19 outbreak reported last week.

Most of the K-5 school’s 500 or so students will return to in-person learning Tuesday, but some will be held out of class while school officials await COVID test results.

Four classrooms will remain closed pending the test results, according to a spokesperson for Portland Public Schools. The district said that additional negative test results were received late Monday afternoon which led to the decision to close just four classrooms. When the outstanding test results have been received the remaining four classrooms will be opened.

The Maine Center for Disease Control and Prevention declared an outbreak at Lyseth on Friday after the district reported nine cases and 38 close contacts at the school. An outbreak occurs when at least three cases are reported within 14 days, and close contacts must go into quarantine. The outbreak appears to be connected to a neighborhood child care facility.

An outbreak does not require a school to close. But after consulting with public health and medical advisers, the district decided to close Lyseth on Monday to determine whether there was any additional exposure at the school. Followup testing was conducted over the weekend and there have been no additional positive results, but a dozen test results are still pending.

Lyseth will inform families directly regarding the status of their child’s classroom and about remote learning plans for quarantined students. The elementary school, at 175 Auburn St., employs about 75 teachers and staff.

“We recognize the challenge that having students out of school presents for students and families,” Portland Public Schools said in a statement. “We thank Lyseth families and their staff for their cooperation and understanding as we balance this with the health and safety of everyone.”

Maine’s largest school district got off to a rough start after Labor Day weekend. Portland High School closed Sept. 7  after two COVID case were reported and 35 close contacts were identified. The high school reopened Wednesday.

Other cases were reported at Deering High School (one case, 33 close contacts); East End Community School (two cases); Lyman Moore Middle School (three cases, 26 close contacts); and Presumpscot Elementary School, (one case, 42 close contacts).

Pooled testing in kindergarten through Grade 6 – whose students are not currently eligible for the COVID vaccine – is slated to start Sept. 20. Pooled testing can detect asymptomatic individuals before they develop symptoms or become infectious. Pooled testing is voluntary, but district officials urge all families with students in kindergarten through grade 6 to register their children as soon as possible.