AMHERST — In-person learning for some students in the Amherst elementary and secondary schools is supposed to begin Thursday, but an outbreak of COVID-19 cases among University of Massachusetts students could affect that plan.

The Amherst Pelham Education Association issued a statement Monday that a cluster of positive COVID tests among off-campus students is prompting the Joint Labor Management Safety Committee, made up of both union representatives and officials from the school, to schedule a meeting for discussing the reopening plans.

“APEA is continuing to work to keep our Amherst Public School students learning and as safe as possible during this pandemic,” the statement reads.

A tentative agreement between the union and district representatives earlier in September calls for preschoolers, kindergartners and first graders, along with special population students at all grade levels, to be in class five days a week beginning Thursday. That agreement, though, also suggests that members of the joint safety committee have a conversation when coronavirus cases in Amherst exceed 28 per 100,000 residents.

With 21 cases reported on the UMass COVID dashboard over the past week, the caseload has risen to 55 positives per 100,000 residents in Amherst, according to the union.

A meeting was scheduled for Tuesday afternoon, in advance of an evening meeting of the Amherst, Pelham and Amherst-Pelham Regional school committees.

On Friday, the university announced that 13 students living off-campus had tested positive for the virus, and this number increased to 18 by Monday. All of the students had socialized with each other, and some had attended a party together.

As of Tuesday afternoon, the number of positives in the cluster was unchanged, but four additional cases not known to be associated with the cluster were identified.

Campus spokesman Ed Blaguszewski said that “the cluster currently remains at 18.” He did not have more information about the new cases.

According to the university’s COVID-19 dashboard, UMass has recorded 43 cases since Aug. 6., up from 39 on Monday.

The university has administered 57,313 tests overall.

The union representing teachers, paraprofessionals and other staff said it will be making recommendations and working to keep families and staff informed. “We understand that this cluster of cases may be causing some anxiety among families, staff, administrators, and School Committee.”

Under the current plan, second and third graders would return to classes Oct. 19, while Grades 4 to 6 and middle and high schoolers would have in-person classes starting Nov. 16.

In addition to regularly testing all students living on-campus, the university announced last Saturday that it would begin directing all off-campus students to come to campus for testing twice a week.

For the recent positive cases, the contact tracing to identify others who may have been exposed is being handled by the university, said Town Manager Paul Bockelman. Typically, for cases in town, the health director and town nurse have done this work.

Scott Merzbach can be reached at smerzbach@gazettenet.com.

Scott Merzbach is a reporter covering local government and school news in Amherst and Hadley, as well as Hatfield, Leverett, Pelham and Shutesbury. He can be reached at smerzbach@gazettenet.com or 413-585-5253.